Votes & seats · United Kingdom · general election, 4 July 2024

Labour won a third of the vote—and nearly two-thirds of the seats.

At the general election on 4 July 2024, Labour won 33.7% of valid UK votes and 411 of 650 seats (63.2%). That describes one result under one set of voter choices; it does not by itself settle which electoral system is better.

Site purpose (informational): Explain how votes become seats and set out the alternatives fairly; no electoral system is recommended.

Evidence last reviewed 3 October 2026

Overview

The short version

Three key measures

Who feels this most?

The effect falls on voters for parties whose support is spread thinly. In 2024, 57.7% of valid votes — 16,626,960 — went to candidates who were not elected. Reform UK voters cast 4,117,610 votes and elected 5 MPs; Green voters cast 1,944,501 and elected 4. Voters in safe seats may also find campaigns concentrated elsewhere. These are facts about how votes were translated, not evidence that any group’s votes were counted differently: every valid vote counts once.

The 2024 result

On 4 July 2024, 28,809,340 valid votes were cast across 650 constituencies, a turnout of 59.7% of 48,224,212 registered electors. Labour won 9,708,716 votes and 411 seats; the Conservatives 6,828,925 votes and 121 seats.

How did votes translate into Commons seats in 2024?

The 2024 vote share and seat share were very different.

Share of valid votes cast and share of the 650 House of Commons seats won, by party, UK general election 4 July 2024.

United Kingdom · 4 July 2024

2024: Labour 33.7% of votes and 63.2% of seats; Conservative 23.7% and 18.6%; Reform UK 14.3% and 0.8%; Liberal Democrat 12.2% and 11.1%.

Share of valid votes

100% of votes

Share of Commons seats

100% of 650 seats

  • Labour: 33.7% of votes → 63.2% of seats (411 seats)
  • Conservative: 23.7% of votes → 18.6% of seats (121 seats)
  • Reform UK: 14.3% of votes → 0.8% of seats (5 seats)
  • Liberal Democrat: 12.2% of votes → 11.1% of seats (72 seats)
  • Green: 6.7% of votes → 0.6% of seats (4 seats)
  • SNP: 2.5% of votes → 1.4% of seats (9 seats)
  • All others: 6.8% of votes → 4.3% of seats (28 seats)

“All others” is Sinn Féin, Plaid Cymru, Democratic Unionist Party, Alliance Party of Northern Ireland, Ulster Unionist Party, Social Democratic and Labour Party, plus independents, the Speaker and smaller parties: 1,965,687 votes and 28 seats in total. Party colours are conventional and have not been checked against each party’s current brand guidance; every segment is also named in the key.

The two bars use the same party order and the same colours. Labour’s 33.7% of votes became 63.2% of seats; Reform UK’s 14.3% became 0.8%. The gap is produced by where votes were cast, not by any vote counting more than another: every valid vote counts once, but only the most-voted candidate in each seat is elected. This chart shows the outcome of one election under one set of voter choices; it does not show what would have happened under different rules.

United Kingdom · 4 July 2024 · Official results; shares are a site calculation

Sources, definitions and data — The 2024 vote share and seat share were very different.
Geography:
United Kingdom — all valid votes in all 650 constituencies, including Northern Ireland, independents and the Speaker
Measure:
% of valid votes; % of seats
Period:
4 July 2024
Status:
Official results; shares are a site calculation
Calculation:
Shares computed from published vote and seat counts. Six parties shown individually; “all others” is the reconciled remainder so each bar sums to 100% (28,809,340 votes; 650 seats).
Compare with:
Each party’s seat share against its own vote share.
Not included / breaks:
Rejected ballots are not valid votes and are excluded, as in the official totals. The 2024 election used new constituency boundaries; national shares are unaffected.

Source: House of Commons Library, General election 2024 results (CBP-10009), national and constituency results files (released 3 March 2026 (dataset revision; record of dataset changes updated 5 January 2026)). Chart VOTE-01.

View the data as a table
PartyVotesVote shareSeatsSeat shareSeat share minus vote share
Labour9,708,71633.7%41163.2%+29.5 pts
Conservative6,828,92523.7%12118.6%−5.1 pts
Reform UK4,117,61014.3%50.8%−13.5 pts
Liberal Democrat3,519,14312.2%7211.1%−1.1 pts
Green1,944,5016.8%40.6%−6.1 pts
All other candidates1,089,0963.8%81.2%−2.5 pts
Scottish National Party724,7582.5%91.4%−1.1 pts
Sinn Féin210,8910.7%71.1%+0.3 pts
Plaid Cymru194,8110.7%40.6%−0.1 pts
Democratic Unionist Party172,0580.6%50.8%+0.2 pts
Alliance Party of Northern Ireland117,1910.4%10.2%−0.3 pts
Ulster Unionist Party94,7790.3%10.2%−0.2 pts
Social Democratic and Labour Party86,8610.3%20.3%+0.0 pts

Scroll the table sideways to see every column.

Put this in scale: 33.7% of the vote, 63.2% of the seats →

Which parties gained or lost in the translation from votes to seats?

Only Labour gained more than a point; 3 parties lost more than five.

Vote share (open circle) and seat share (filled circle) by party, with the percentage-point difference, UK general election 2024.

United Kingdom · 4 July 2024
Seat shareVote share
  • Labour (+29.5 pts)63.2%
  • Conservative (−5.1 pts)18.6%
  • Reform UK (−13.5 pts)0.8%
  • Liberal Democrat (−1.1 pts)11.1%
  • Green (−6.1 pts)0.6%
  • Scottish National Party (−1.1 pts)1.4%
  • Sinn Féin (+0.3 pts)1.1%
  • Plaid Cymru (−0.1 pts)0.6%
  • Democratic Unionist Party (+0.2 pts)0.8%
  • Alliance Party of Northern Ireland (−0.3 pts)0.2%
  • Ulster Unionist Party (−0.2 pts)0.2%
  • Social Democratic and Labour Party (+0.0 pts)0.3%
Labour is the only party whose seat share exceeded its vote share by more than a point (+29.5 pts). Reform UK (−13.5 pts) and the Greens (−6.1 pts) won far fewer seats than their vote shares, because their votes were spread across many constituencies they did not win. Several Northern Ireland parties and Plaid Cymru, whose votes are concentrated, are close to proportional. Votes per seat describe the geography of support, not the value of a ballot.

United Kingdom · 4 July 2024 · Official results; differences are a site calculation

Sources, definitions and data — Only Labour gained more than a point; 3 parties lost more than five.
Geography:
United Kingdom
Measure:
percentage of valid votes and of seats; difference in percentage points
Period:
4 July 2024
Status:
Official results; differences are a site calculation
Calculation:
Seat share minus vote share, in percentage points. Independents and minor parties are grouped as “all other candidates” in the table, not plotted, because they are not one party.
Compare with:
A party whose two circles coincide won seats in proportion to its votes.

Source: House of Commons Library, General election 2024 results (CBP-10009), national and constituency results files (released 3 March 2026 (dataset revision; record of dataset changes updated 5 January 2026)). Chart VOTE-02.

View the data as a table
PartyVotesVote shareSeatsSeat shareSeat share minus vote share
Labour9,708,71633.7%41163.2%+29.5 pts
Conservative6,828,92523.7%12118.6%−5.1 pts
Reform UK4,117,61014.3%50.8%−13.5 pts
Liberal Democrat3,519,14312.2%7211.1%−1.1 pts
Green1,944,5016.8%40.6%−6.1 pts
All other candidates1,089,0963.8%81.2%−2.5 pts
Scottish National Party724,7582.5%91.4%−1.1 pts
Sinn Féin210,8910.7%71.1%+0.3 pts
Plaid Cymru194,8110.7%40.6%−0.1 pts
Democratic Unionist Party172,0580.6%50.8%+0.2 pts
Alliance Party of Northern Ireland117,1910.4%10.2%−0.3 pts
Ulster Unionist Party94,7790.3%10.2%−0.2 pts
Social Democratic and Labour Party86,8610.3%20.3%+0.0 pts

Scroll the table sideways to see every column.

How 650 local contests add up

A general election is 650 separate contests. In each, the candidate with more votes than any other wins; there is no threshold and no second round. A party that comes a close second everywhere can win almost nothing, while a party that wins many seats narrowly can win a majority. 115 seats were decided by a margin of under five percentage points. The lowest winning share was 26.7% in South West Norfolk (11,847 of 44,335 votes) — a normal result when many candidates stand.

How much of the local vote did winning candidates need?

554 of 650 MPs were elected on less than half the votes in their constituency.

Number of constituencies by the winning candidate’s share of valid votes in that constituency, 2024.

United Kingdom, 650 constituencies · 4 July 2024
  • Under 35% of the local vote100 seats
  • 35% to under 40%164 seats
  • 40% to under 50%290 seats
  • 50% or more96 seats
Only 96 MPs won a majority of the votes cast locally. Across all seats, 57.7% of valid votes (16,626,960) went to candidates who were not elected. That is a fact about this election, not a verdict that those votes were “wasted”: whether a vote that elects nobody still matters is a question about what voting is for. A low winning share is also normal when many candidates stand.

United Kingdom, 650 constituencies · 4 July 2024 · Official results; bands are a site convention

Sources, definitions and data — 554 of 650 MPs were elected on less than half the votes in their constituency.
Geography:
United Kingdom, 650 constituencies
Measure:
number of constituencies
Period:
4 July 2024
Status:
Official results; bands are a site convention
Calculation:
Winning candidate’s votes divided by valid votes in the constituency, grouped into bands chosen by this site.
Compare with:
Under First Past the Post a candidate needs more votes than any other candidate, not a majority.

Source: House of Commons Library, General election 2024 results (CBP-10009), national and constituency results files (released 3 March 2026 (dataset revision; record of dataset changes updated 5 January 2026)). Chart VOTE-03.

View the data as a table
Winning share bandConstituencies
Under 35% of the local vote100
35% to under 40%164
40% to under 50%290
50% or more96

Is 2024 unusual?

The long-run record has to use coarser party groups, because results before 2024 do not separate Reform UK, the Greens or Northern Ireland parties. On that consistent basis the gap between votes and seats was 26.4 on the Gallagher index in 2024, the highest since 1945.

Has the gap between votes and seats changed over time?

On a consistent five-group basis, 2024 had the largest gap between votes and seats since 1945.

Gallagher least-squares index of disproportionality, UK general elections 1945–2024, five party groups (Conservative; Labour; Liberal/Alliance/Liberal Democrat; SNP and Plaid Cymru; all others).

United Kingdom · 1945–2024 (21 elections, both 1974 elections shown)

1996–2026 displayed window · observations only. Shading marks years outside the displayed record.

Gallagher index010203020002010202026.4
The index rose from 2.9 in 1951 to 26.4 in 2024. Higher values mean a larger aggregate gap between vote and seat shares; they are not a fairness score. The rise tracks voters spreading across more parties while the Commons stays dominated by two: the effective number of parties by votes went from 2.9 in 1979 to 3.9 in 2024, by seats from 2.1 to 2.2 (five-group basis).

United Kingdom · 1945–2024 (21 elections, both 1974 elections shown) · Established academic measure; site calculation from official results

Sources, definitions and data — On a consistent five-group basis, 2024 had the largest gap between votes and seats since 1945.
Geography:
United Kingdom
Measure:
index (0 = seat shares exactly match vote shares)
Period:
1945–2024 (21 elections, both 1974 elections shown)
Status:
Established academic measure; site calculation from official results
Calculation:
√(½ × Σ(vote share − seat share)²) over the five groups, computed by this site from the Commons Library results; 2024 from CBP-10009 regrouped to the same five groups.
Compare with:
Lowest 2.9 (1951); highest 26.4 (2024).
Not included / breaks:
Reform UK, the Greens, UKIP and Northern Ireland parties are inside “all others” for every year, so the series is consistent but coarse. The 2024 full-detail index is a different number and is not plotted.

Source: House of Commons Library, General election results from 1918 to 2019 (CBP-8647), UK summary results (released 17 April 2020). Chart VOTE-04.

View the data as a table
ElectionGallagher indexEffective parties (votes)Effective parties (seats)Turnout
194511.712.652.0972.2%
19507.212.612.1983.9%
19512.862.332.2582.6%
19554.112.162.0376.8%
19597.312.281.9978.7%
19648.892.532.0677.1%
19668.422.422.0375.8%
19706.632.462.0772.0%
Feb 197415.473.132.2678.8%
Oct 197414.983.142.2572.8%
197911.612.862.1576.0%
198320.573.112.0971.8%
198717.743.072.1775.3%
199213.593.052.2777.7%
199716.523.192.1271.3%
200117.933.282.1759.4%
200516.923.522.4661.5%
201015.563.612.5865.1%
201516.433.632.5466.2%
20176.762.852.4768.8%
201912.183.172.3867.3%
202426.363.852.2259.7%

Scroll the table sideways to see every column.

On what share of the vote have governments been formed?

Every post-war government, all 22, was formed by a party with less than half the votes.

Vote share and seat share of the party that formed the government (the larger partner in 2010), UK general elections 1945–2024.

United Kingdom · 1945–2024

1996–2026 displayed window · observations only. Shading marks years outside the displayed record.

% of votes or seats0%20%40%60%200020102020Half63.2%33.7%
In 18 of 22 elections a party won a majority of seats on a minority of votes. Supporters of First Past the Post regard this as the system working: it tends to turn a lead into a governing majority that voters can later remove. Critics regard the same pattern as the system’s main cost. The chart cannot settle which matters more; it shows how often the trade-off has applied.

United Kingdom · 1945–2024 · Official results

Sources, definitions and data — Every post-war government, all 22, was formed by a party with less than half the votes.
Geography:
United Kingdom
Measure:
% of valid votes; % of seats
Period:
1945–2024
Status:
Official results
Calculation:
As published; government type recorded per election from the outcome, not inferred from seats.
Compare with:
50% reference: a majority of votes or seats.
Not included / breaks:
2010 shows the Conservative share only; the coalition partner’s votes and seats are not added. 1951 and February 1974: the party with the most votes did not form the government.

Source: House of Commons Library, General election results from 1918 to 2019 (CBP-8647), UK summary results (released 17 April 2020). Chart VOTE-05.

View the data as a table
ElectionFormed byVote shareSeat share
1945Labour48.1%61.8%
1950Labour46.1%50.4%
1951Conservative44.0%47.3%
1955Conservative49.6%54.6%
1959Conservative49.4%57.9%
1964Labour44.1%50.3%
1966Labour47.9%57.6%
1970Conservative46.4%52.4%
Feb 1974Labour37.1%47.4%
Oct 1974Labour39.3%50.2%
1979Conservative43.9%53.4%
1983Conservative42.4%61.1%
1987Conservative42.3%57.8%
1992Conservative41.9%51.6%
1997Labour43.2%63.4%
2001Labour40.7%62.5%
2005Labour35.2%55.0%
2010Conservative–Liberal Democrat coalition36.1%47.1%
2015Conservative36.8%50.8%
2017Conservative42.3%48.8%
2019Conservative43.6%56.2%
2024Labour33.7%63.2%

Scroll the table sideways to see every column.

Who feels this most?

Parties whose support is concentrated in one nation, such as Plaid Cymru and the Northern Ireland parties, are close to proportional under the current system (VOTE-02) — and would be among the first excluded by a UK-wide 5% threshold (chapter 4).

What other counting rules would do — an illustration

This is not a forecast. This is an illustration, not a prediction. Under a different electoral system, voters, parties and campaigns would behave differently. It shows how the same national votes would map to seats under the named allocation method — not what the result “would have been”. A UK-wide allocation is an artificial illustration. Parties do not all contest every part of the UK, and real proportional systems normally use regional or multi-member constituencies rather than treating the whole country as one constituency — which produces less proportional results than the figures here.
Allocation method

Largest remainder, Hare quota. Divide total votes by the number of seats to get a quota. Each party gets one seat per whole quota it holds. Any seats still unallocated go to the parties with the largest remainders. Close to neutral between large and small parties, which is why it is the default here — it answers the "as closely as possible to vote share" question with the least distortion of its own.

  • Labour33.7% of votes → 411 seats actual
  • Conservative23.7% of votes → 121 seats actual
  • Reform UK14.3% of votes → 5 seats actual
  • Liberal Democrat12.2% of votes → 72 seats actual
  • Green6.7% of votes → 4 seats actual
  • All other candidates3.8% of votes → 8 seats actual
  • Scottish National Party2.5% of votes → 9 seats actual
  • Sinn Féin0.7% of votes → 7 seats actual
  • Plaid Cymru0.7% of votes → 4 seats actual
  • Democratic Unionist Party0.6% of votes → 5 seats actual
  • Alliance Party of Northern Ireland0.4% of votes → 1 seats actual
  • Ulster Unionist Party0.3% of votes → 1 seats actual
  • Social Democratic and Labour Party0.3% of votes → 2 seats actual

Bars share one scale, set by the largest seat count shown. Total seats allocated: 650.

This is an illustration, not a prediction. Under a different electoral system, voters, parties and campaigns would behave differently. It shows how the same national votes would map to seats under the named allocation method — not what the result “would have been”.

And a UK-wide allocation is artificial. Parties do not all contest every part of the UK, and real proportional systems normally use regional or multi-member constituencies rather than treating the whole country as one constituency — which produces less proportional results than the figures here.

Formulas: largest remainder (Hare quota) — quota = totalVotes / totalSeats; seats = floor(votes / quota), remaining seats to the largest (votes mod quota); D’Hondt — quotient = votes / (seatsWon + 1); highest quotient takes each successive seat; Sainte-Laguë — quotient = votes / (2 × seatsWon + 1); highest quotient takes each successive seat. Source votes: House of Commons Library CBP-10009. Illustration computed by this site.

A mixed-member design that kept every 2024 constituency winner and added top-up seats until no party was over-represented would need a chamber of 1,220 (650 constituency MPs plus 570 top-ups). Compensation can only add seats, so the more skewed the constituency result, the larger the chamber. Real mixed-member systems give voters two votes — one for a constituency candidate, one for a party list — and many people split them between parties. The 2024 election had no second vote, so this model reuses the single First Past the Post vote for both purposes, which no real system does. It also enlarges the Commons rather than reducing the number of constituencies, which is one of several designs a real reform could take.

The trade-offs: representation, locality and government formation

There is no statistically correct electoral system. Each puts different weight on three things that pull against each other. Supporters of First Past the Post point to a single identifiable local MP, a simple ballot and count, and decisive outcomes: in 18 of 22 post-war elections a party won a majority of seats on a minority of votes, which they regard as the system turning a lead into a government voters can later remove. Supporters of proportional systems regard the same pattern as the main cost, and point to the share of votes that elect nobody.

Ranked ballots (Alternative Vote, Single Transferable Vote) reduce the incentive to vote tactically, because a lower preference still counts. Proportional systems make coalition or minority government more common; whether that makes government less stable or more consensual is argued both ways, and comparing countries cannot isolate the electoral system from everything else that differs between them. No national tactical-voting figure is shown here: ballots record a cross, not a motive.

The UK already uses four systems
InstitutionSystemHow it works
House of CommonsFirst Past the Post650 single-member constituencies. One cross, most votes wins, no threshold and no second round.
Local councils in England and WalesFirst Past the PostSingle- and multi-member wards, each elected on the same plurality basis.
Senedd Cymru / Welsh ParliamentClosed-list proportional representation (since May 2026)96 Members across 16 constituencies, six per constituency. Voters cast one vote for a party list or an independent, and seats are allocated by the D’Hondt method. This replaced the previous additional member system.
Scottish ParliamentAdditional member systemConstituency MSPs elected by First Past the Post, plus regional MSPs allocated to bring each region closer to proportionality. Voters cast two votes.
Northern Ireland AssemblySingle Transferable VoteMulti-member constituencies with ranked ballots. Candidates are elected on reaching a quota, with surpluses and eliminated candidates’ votes transferred by preference.
Local councils in Northern IrelandSingle Transferable VoteThe same ranked, multi-member method used for the Assembly.
Local councils in ScotlandSingle Transferable VoteMulti-member wards with ranked ballots, used since 2007.

Source: House of Commons Library SN04458. The 96-member Senedd was first elected by closed list in May 2026 (turnout 51.6%, Electoral Commission).

Which reforms have political support?

The last direct public decision was the 2011 referendum on the Alternative Vote: 67.9% voted No on a 42.2% turnout (House of Commons Library RP11-44). Positions now differ by party, and so does the weight of the documents behind them — a conference motion, a consultation paper and a manifesto are not the same thing. Labour is the row that shows why this table has three separate columns rather than one. Conference voted in 2022 that the party must commit to proportional representation in its next manifesto. The 2024 manifesto contains no reference to the electoral system at all — verified by searching the published document. And there is no government programme to change it. Conference position, manifesto commitment and government policy are three different things, and on this issue they do not agree with each other.

Public attitudes to specific alternatives are not reported on this page: survey results vary with question wording, and we have not yet reviewed a consistent series. Where a party’s current position could not be checked against its own document, it is shown as unverified rather than filled in.

  • Liberal Democrats

    Supports PR

    Support replacing First Past the Post with proportional representation. Existing party policy is the Single Transferable Vote for MPs.

    Preferred system: Single Transferable Vote

    2024 manifesto
    Official policy

    Campaigns for proportional representation, described as making seats won match votes cast.

    Party source ↗

    Verified 2026-08-16

    Conference position
    Conference position

    Autumn 2024 conference motion F29 calls on the Government to replace First Past the Post for UK general elections with proportional representation by the Single Transferable Vote, and to introduce STV for local councillors in England.

    Party source ↗

    Verified 2026-08-16

    Government policy
    Not in government

    Other documents

    Internal consultation

    The Spring 2026 'Defending Democracy' consultation paper states on its face that it does not represent agreed party policy, while separately identifying existing policy as STV for MPs.

    Party source ↗

    Verified 2026-08-16

  • Green Party of England and Wales

    Supports PR

    Support replacing First Past the Post with a proportional system. The manifesto does not name a specific system.

    Preferred system: not specified in the sources checked

    2024 manifesto
    Official policy

    Elected Greens will push for replacing the first past the post system for parliamentary elections with a fair and proportional voting system.

    Party source ↗

    Verified 2026-08-16

    Conference position
    None recorded
    Government policy
    Not in government

  • Labour

    Internal support, no commitment

    Party conference voted in 2022 for a commitment to proportional representation. The 2024 general election manifesto contained no such commitment, and there is no government programme to change the Westminster voting system.

    Preferred system: not specified in the sources checked

    2024 manifesto
    Official policy

    The manifesto contains no reference to proportional representation, First Past the Post, the electoral system or electoral reform. It does commit to House of Lords reform and votes at 16.

    Party source ↗

    Verified 2026-08-16

    Conference position
    Conference position

    The 2022 conference carried a motion resolving that Labour must commit to introducing proportional representation for general elections in the next manifesto, and change the voting system during its first term in office.

    Party source ↗

    Verified 2026-08-16

    Government policy
    Official policy

    No programme to introduce proportional representation for Westminster elections.

    Party source ↗

    Verified 2026-08-16

  • Conservative

    Needs verificationOpposes changing the system

    Historically defend First Past the Post for Westminster elections. The current position has not been verified against a post-2024 party source.

    Preferred system: First Past the Post

    2024 manifesto
    Not verified — checking
    Conference position
    None recorded
    Government policy
    Historical position

    The then-Government position recorded by the House of Commons Library was that First Past the Post should be retained for Westminster elections.

    Party source ↗

    Verified 2026-08-16

  • Reform UK

    Needs verificationNot verified — checking

    Position to be verified against the latest party manifesto or policy statement.

    Preferred system: not specified in the sources checked

    2024 manifesto
    Not verified — checking
    Conference position
    None recorded
    Government policy
    Not in government

  • Scottish National Party

    Needs verificationNot verified — checking

    Westminster electoral-reform commitment to be verified against the latest party manifesto.

    Preferred system: not specified in the sources checked

    2024 manifesto
    Not verified — checking
    Conference position
    None recorded
    Government policy
    Not in government

Positions checked against each party’s own documents on 16 August 2026.

Shareable visual summary

Visual summary

Image current

Every figure printed in the image matches today’s record, and its primary sources have been checked.

Labour won a third of the vote—and nearly two-thirds of the seats.

At the general election on 4 July 2024, Labour won 33.7% of valid UK votes and 411 of 650 seats (63.2%). That describes one result under one set of voter choices; it does not by itself settle which electoral system is better. A past result (4 July 2024), not current polling or party strength.

Labour at the 2024 general election (0–100%)

  • Share of votes33.7%
  • Share of seats63.2%
UK general election, 4 July 2024. Source: House of Commons Library.
Download image (PNG, 1024 by 1536 pixels)

Labour won a third of the vote—and nearly two-thirds of the seats.

Electoral system infographic: Labour won 33.7% of votes and 411 of 650 seats (63.2%) at the 4 July 2024 general election.
Text and data version

Labour won a third of the vote—and nearly two-thirds of the seats. At the general election on 4 July 2024, Labour won 33.7% of valid UK votes and 411 of 650 seats (63.2%). That describes one result under one set of voter choices; it does not by itself settle which electoral system is better. A past result (4 July 2024), not current polling or party strength.

Records behind this visual summary
MeasureValuePeriodGeographyTypeSource
Labour share of the UK vote33.7%4 July 2024United Kingdomobserved countUK Parliament election results, general election 4 July 2024
Labour seats won4114 July 2024United Kingdomobserved countUK Parliament election results, general election 4 July 2024
House of Commons seats6504 July 2024United Kingdomobserved countUK Parliament election results, general election 4 July 2024
Labour share of Commons seatsCalculation: seats won ÷ 650 × 10063.2%4 July 2024United Kingdomderived calculationUK Parliament election results, general election 4 July 2024

Image description: Electoral system infographic: Labour won 33.7% of votes and 411 of 650 seats (63.2%) at the 4 July 2024 general election.

All visual summaries, their source records and their publication state are listed on Shareable visuals.

Go deeper

Evidence → choices → outcomes

What the evidence can tell us

An informed democratic choice about how votes become seats, made with a clear view of what each system gains and gives up in proportionality, local representation and accountability.

Participation depends on practical access

The voting system also needs to be accessible. The Electoral Commission’s review of the May 2026 elections recommends improving the Voter Authority Certificate; votes-to-seats comparisons alone do not capture barriers to participation.

Evidence in the domain SWOT →

This domain in the UK SWOT →UK National Action Plan →

How we assessed these options

What would it take to improve this?

What would move the needle?

The outcome we want: An informed democratic choice about how votes become seats, made with a clear view of what each system gains and gives up in proportionality, local representation and accountability.

The main constraint: Any change needs an Act of Parliament passed by MPs elected under the current system and, by the 2011 precedent, a referendum — and there is no agreed public process or fair comparison to inform that choice.

Constraint type: legislation, public consent, evidence.

The position today

  • What we can build on (2)
  • What is holding us back (3)The voting system also needs to be accessible. The Electoral Commission’s review of the May 2026 elections recommends improving the Voter Authority Certificate; votes-to-seats comparisons alone do not capture barriers to participation. (Electoral Commission, 2026 · England)
  • What could improve things (2)A representative citizens’ assembly could examine the voting system with balanced evidence; the 2021 UK assembly on democracy left this question out and said a future assembly could take it up.
  • What could make it worse (1)

Which quadrant a point sits in is our analytical judgement, not a statistical category. Each point says whether it is a measured fact, our synthesis or a risk.

What we can build on Strengths

What is holding us back Weaknesses

What could improve things Opportunities

What could make it worse Threats

The actions worth examining

These actions concern transparency, accountability and informed choice — not a spending programme, and not a view on which party or system is right.

  1. Give electoral reform an informed public decision process — not yet costed / funding not identified
  2. Compare voting systems without pretending votes stay unchanged — not a direct public-spending programme

  • Action 1A33Policy status: external proposal

    Give electoral reform an informed public decision process

    A representative citizens’ assembly hears balanced evidence on representation, proportionality and accountability and makes advisory recommendations that Parliament commits in advance to answer.

    The thread: issue, evidence, action

    1. Issue Weakness: Votes and seats can diverge sharply: Labour won 33.7% of votes and 63.2% of seats in 2024, and 554 of 650 MPs won with less than half their local vote. Also: opportunity
    2. Evidence Formal response to a deliberative process on the voting system
    3. Action A33, this action
    Who decides:
    UK Government or Commons committees (commissioning), an independent organiser, and Parliament (any change, by the 2011 precedent with a referendum) (UK)
    Evidence:
    Expert or audit recommendation. Evidence on deliberative process from a UK assembly that explicitly excluded electoral systems; it cannot show which system is better or whether an assembly changes a reform decision.
    Expected effect:
    Direction plausible; size not established.
    Cost and funding

    Not yet costed

    Funding: Not yet costed / funding not identified

    Why it is shortlisted here: Improves how the choice is made rather than choosing a system; it replaces the existing assembly option, now with the scope limits of the 2021 assembly stated.

    What it takes
    The problem

    Whether to change the Westminster voting system is decided by MPs elected under the current one, and the last public decision, the 2011 referendum, offered a single alternative.

    Who is affected, and where

    UK voters. Territory: UK. House of Commons elections only. Scottish Parliament, Senedd and Northern Ireland Assembly elections already use other systems.

    Policy status

    Proposed by researchers or others, not government policy. Not government policy. The UK has commissioned assemblies on other questions (Climate Assembly UK, 2020). The 2021 Citizens’ Assembly on Democracy in the UK deliberately did not consider electoral systems and said a future assembly could examine them.

    The evidence
    What the research found:
    The assembly did not consider “the best electoral system for choosing MPs” and said a future assembly could usefully examine it. Its members backed using deliberative processes more often (Resolution 5, supported by 90%) and wanted results to be advice to decision-makers, not binding (Recommendation 5.2, 85%). These are members’ votes, not population opinion.
    Evaluated on:
    67 members recruited to be representative of UK adults; Online, six weekends, October–December 2021
    Our recommendation (separate from the research):
    If Parliament wants to consider reform, agree the remit, the options, how evidence is governed and the formal response before recruiting — and treat the result as advice, not as national opinion.
    Strongest counter-evidence:
    Elected MPs, and voters in a referendum, are the legitimate decision-makers; the 2011 referendum rejected the one alternative offered, and an assembly can add delay or be seen as framed towards an outcome.
    Cost and funding

    Cost completeness: Not yet costed. Funding: Not yet costed / funding not identified.

    • Citizens’ assembly on the Westminster voting system (administration; paid by central government): Not yet costed. No contemporary national price was found; the 2021 assembly report does not give its cost.
    Who pays:
    Whoever commissions it (government or Parliament); assembly members are usually paid for their time.
    Financing proposed:
    A named commissioning budget. It is not funded by assumed savings elsewhere in Parliament.
    Gap remaining:
    Unknown: recruitment, facilitation, evidence, accessibility and administration have not been costed for a contemporary national assembly.
    What delivery needs
    Skills:
    An independent organiser, facilitators and balanced expert witnesses.
    Operational capacity:
    Civic-lottery recruitment.
    Infrastructure:
    Venues or an online platform with accessibility support.
    Permissions:
    None.
    Law:
    None to hold an assembly; any change to the voting system needs an Act of Parliament.
    Public consent:
    A prior government or parliamentary commitment to respond formally.
    First step and stages

    First step: Agree the remit, the options, how evidence is governed and what will happen to the recommendations. (owner: UK Government or Commons committees)

    1. Agree remit and response route — Government or Commons committees (proposed stage, not an official timetable)
    2. Run the assembly — Independent organiser (proposed stage, not an official timetable)
    3. Formal response; any legislation or referendum — Parliament (proposed stage, not an official timetable)

    Depends on: A34: a fair, bounded comparison of systems to inform the evidence

    Trade-offs
    Who gains and who loses:
    Affects every voter; parties that would gain or lose seats under each system have opposing stakes in the outcome.
    What else the money or effort could do:
    Parliamentary and ministerial time, and the assembly budget.
    Strongest counterargument:
    Representative institutions already decide constitutional questions, with referendums as the established public test; an unelected assembly may lack legitimacy.
    Risks:
    Agenda-setting by whoever frames the options, a weak connection to an actual decision, and treating assembly preferences as national opinion.
    How we would judge it
    Baseline:
    No UK citizens’ assembly has examined the Westminster voting system.
    Leading indicator:
    Representativeness of members and balance of evidence, judged by an independent process review.
    Outcome:
    A published recommendation and a formal, reasoned government or parliamentary response.
    Continue, adapt or stop:
    Treat it as failed if an independent reviewer finds the remit or evidence unbalanced, or if no formal response is made.
    Earlier option on this page

    This card replaces the option “A citizens’ assembly to recommend whether to change” (external option). Its evidence: The UK has used the method on other questions (Climate Assembly UK, commissioned by six Commons select committees, reported in 2020). Its recommendations are advisory; there is no UK evidence on whether an assembly changes the outcome of an electoral-reform decision. Climate Assembly UK, The path to net zero (final report)

    Sources

    Source published April 2022 (assembly held in 2021); evidence reviewed 2026-10-04. Reconsider if: The government or a Commons committee commits to reviewing the voting system; A governing party adopts a reform proposal; A new UK deliberative process on elections is announced.

  • Action 2A34Policy status: site-editorial action

    Compare voting systems without pretending votes stay unchanged

    Publish a transparent comparison of systems with clearly bounded illustrative seat calculations, stating what each illustration cannot predict.

    The thread: issue, evidence, action

    1. Issue Weakness: Votes and seats can diverge sharply: Labour won 33.7% of votes and 63.2% of seats in 2024, and 554 of 650 MPs won with less than half their local vote. Also: threat, opportunity
    2. Evidence Gallagher index of disproportionality, general election
    3. Action A34, this action
    Who decides:
    UK Facts (the explanation); Parliament (any change to electoral law) (UK)
    Evidence:
    Untested proposal. An editorial method rather than an intervention with an evaluated effect. The arithmetic rests on official results; how readers understand it has not yet been tested.
    Expected effect:
    Direction plausible; size not established.
    Cost and funding

    Not yet costed

    Funding: Not a direct public-spending programme

    Why it is shortlisted here: Makes the comparison on this page fair and bounded, so no system is shown as a forecast winner.

    What it takes
    The problem

    Recalculations of the 2024 result under other systems are often quoted as if they were forecasts, although voters, parties and turnout would behave differently under different rules.

    Who is affected, and where

    Readers of this site and anyone using the 2024 result to argue for or against reform. Territory: UK. Westminster only; systems used in Scotland, Wales and Northern Ireland are shown as UK experience, not as forecasts.

    Policy status

    UK Facts proposal. Builds on chapter 4 of this page, which already applies three allocation formulas to the 2024 votes as if the UK were one constituency and labels them illustrations.

    The evidence
    What the research found:
    The House of Commons Library results show exactly how 2024 votes became seats. How votes would have been cast under another system is not observed, so any reallocation is an illustration, not a forecast.
    Evaluated on:
    Not applicable: reader comprehension not yet tested; This site
    Our recommendation (separate from the research):
    Define systems, boundaries and assumptions; list the comparisons that cannot be calculated reliably; have the explanation peer-reviewed; and test whether readers can tell votes, seats and preferences apart before release.
    Strongest counter-evidence:
    Any recalculation invites misuse: even a labelled illustration frames the debate around seat counts and can be read as a prediction.
    Cost and funding

    Cost completeness: Not yet costed. Funding: Not a direct public-spending programme.

    • Method, peer review and comprehension testing of the systems comparison (private contribution; paid by UK Facts): Not yet costed. Site staff time; no public cost. Any official review of the voting system would be costed separately.
    Who pays:
    UK Facts: research, data and development time. No public cost; any official review would be costed separately.
    Financing proposed:
    UK Facts’ editorial and product budget.
    Gap remaining:
    Staff time not costed.
    What delivery needs
    Skills:
    Electoral-systems expertise and an independent reviewer.
    Operational capacity:
    Editorial time.
    Infrastructure:
    Existing official results data.
    Permissions:
    None.
    Law:
    None.
    Public consent:
    None.
    First step and stages

    First step: Define systems, boundaries, assumptions and the comparisons that cannot be calculated reliably. (owner: UK Facts editors)

    1. Draft the method and its limits — UK Facts editors (proposed stage, not an official timetable)
    2. Peer review — Independent electoral-systems reviewer (proposed stage, not an official timetable)
    3. Comprehension test, then publish — UK Facts editors (proposed stage, not an official timetable)
    Trade-offs
    Who gains and who loses:
    No direct distributional effect; the risk is presentation that favours one side of the reform debate.
    What else the money or effort could do:
    Editorial time not spent on other pages.
    Strongest counterargument:
    Only behavioural models or real elections under new rules can show what a system would produce; fixed-vote arithmetic may mislead more than it informs.
    Risks:
    False precision, illustrations read as forecasts, and omitting systems that cannot be illustrated.
    How we would judge it
    Baseline:
    The current chapter 4 illustration and its labels.
    Leading indicator:
    Peer-review sign-off; reproducible code and data.
    Outcome:
    In comprehension testing, the share of readers who correctly say an illustration is not a forecast.
    Continue, adapt or stop:
    Withdraw or relabel any illustration that testing shows is commonly read as a prediction.
    Sources

    Source published House of Commons Library, 2024 general election results (CBP-10009); evidence reviewed 2026-10-04. Reconsider if: A new general election result is ingested; Peer-review findings; Comprehension-test results.

Decision brief

  • Let a citizens’ assembly weigh three fully specified voting systems — and agree in advance what Parliament does with the answer

The leading option set out as a decision someone could take: who decides, who benefits, the best evidence, cost and funding, and the main trade-off. The full research record is one click away.

Decision briefStatutory/accountability reformReviewed 2026-10-04

Let a citizens’ assembly weigh three fully specified voting systems — and agree in advance what Parliament does with the answer

The thread: issue, evidence, action

  1. Issue Weakness: Votes and seats can diverge sharply: Labour won 33.7% of votes and 63.2% of seats in 2024, and 554 of 650 MPs won with less than half their local vote. Also: opportunity
  2. Evidence Formal response to a deliberative process on the voting system
  3. Action Give electoral reform an informed public decision process
Decision required
The government or a Commons committee commissions a representative citizens’ assembly to compare three fully specified options for electing MPs — keeping first past the post, a New Zealand-style mixed-member proportional system, and the single transferable vote — and commits beforehand to a formal response and, if change is recommended, to an indicative referendum before any binding one.
Who and where
UK voters. Applies in: UK.
Accountable body
UK government (Cabinet Office) or the Commons Public Administration and Constitutional Affairs Committee
Intervention
Give a representative group of citizens balanced evidence on three fully specified systems and commit Parliament to answer its recommendation.
Best evidence, and where it applies
New Zealand moved to MMP through an independent Royal Commission (1986), an indicative referendum (1992: 84.7% for change) and a binding one (1993: 53.9% for MMP), and kept it in 2011 (57.77%). The UK’s 2021 citizens’ assembly on democracy left the voting system out and said a future assembly could examine it.Studied in: New Zealand voters and elections (1986 to 2023).How closely the comparison transfers to this decision: New Zealand — partial.
Extra cost of this change
Capital: none identified in the brief.Recurring: none identified in the brief.One-off or mixed: Citizens’ assembly: recruitment, member payments, facilitation, evidence, accessibility and administration — Not yet costed; Method, peer review and comprehension testing of the site’s systems comparison — Not yet costed.
Funding
Not funded: no funding route identified yet.Committed to this change: none.Possible source, not an award: none identified.Unfunded: No contemporary national price found; the 2021 assembly report does not give its cost.
Savings and wider benefits
Not yet specified: no cashable saving or avoided cost has been costed for this change. Expected outcomes are listed one by one in the research appendix and are never added together or counted as money available.
First 90-day step
A published remit naming the three options, the evaluation criteria, the evidence-governance arrangements and the commitment on what happens to the recommendationThe proposed first milestone; a 90-day date is not yet specified. Owner: UK government or the commissioning Commons committee. Proposed by UK Facts, not an official deadline.
Twelve-month milestone
Not yet specified.Time to a first useful result: About a year from commissioning to recommendation.
Outcome, and when to scale or stop
Measure: Representativeness of members and balance of evidence, judged by an independent process review.Scale if: The process review finds the remit and evidence balanced and a formal response is made.Stop if: An independent reviewer finds the remit or evidence unbalanced, or no formal response is made — then treat the assembly as failed, as the action’s own rule states.
Main trade-off
An assembly adds time and its framing can be contested; without it, MPs elected under the current rules decide alone, and the last public choice (2011) offered one alternative.
Source and review date
How are MPs elected? and A Royal Commission and two referendums (Pages read via archive copies of December 2025 and January 2026); Report of the Citizens’ Assembly on Democracy in the UK (April 2022). Reviewed 2026-10-04.

An editorial proposal by UK Facts for discussion, not government policy. Records: A33, A34 · costs C-A33-ASSEMBLY, C-A34-EDITORIAL

Research appendix: study design, effect sizes and limits, alternatives, full costing, international comparisons and how we would know

1.The change, in plain words

Let a citizens’ assembly weigh three fully specified voting systems — and agree in advance what Parliament does with the answer

2.The decision requested

Decision
Commission an advisory citizens’ assembly with a fixed remit (three specified options, criteria including constituency link, proportionality, ballot design, thresholds and government formation), independent evidence governance, and an advance commitment to a reasoned government response within a set period and to a two-stage referendum route if change is recommended.
Accountable institution
UK government (Cabinet Office) or the Commons Public Administration and Constitutional Affairs Committee
Geography
UK
Powers
An assembly can be commissioned without legislation, but it can only advise. Changing the Westminster system needs an Act of Parliament; a referendum needs its own Act (as in 2011). Devolved legislatures already set their own systems.
Delivery partners
An independent organiser (deliberation and recruitment); An evidence and advisory panel balanced across views; The Electoral Commission (ballot design and administration advice); The House of Commons Library (results data)

3.Who it is for, and what changes beyond today

Target population
UK voters.
Eligibility
Assembly members selected by stratified random sampling to reflect the UK electorate; the remit covers Westminster elections only.
Scale
One national assembly.
Baseline
In 2024 Labour won 33.7% of votes and 63.2% of seats; 554 of 650 MPs won with less than half the vote in their seat. The 2011 referendum rejected the alternative vote. The UK already uses other systems: the additional member system in Scotland, the single transferable vote in Northern Ireland and Scottish councils, and from 2026 a closed-list system for the Senedd (16 constituencies electing six members each).

Source: House of Commons Library, General election 2024 results (CBP-10009) (National and constituency results files); House of Commons Library, Electoral systems across the UK (SN04458) (Systems used for each UK institution); legislation.gov.uk, Senedd Cymru (Members and Elections) Act 2024: explanatory notes (Overview; sections 1–2)

Change beyond existing law or funding
No UK citizens’ assembly has examined the Westminster voting system. The change is a commissioned assembly with specified options and an agreed route from its advice to Parliament and the public. The site’s own seat illustrations stay labelled as illustrations, not forecasts.

4.How it would work

Do: Give a representative group of citizens balanced evidence on three fully specified systems and commit Parliament to answer its recommendation Changing: so that any decision on the voting system rests on an informed, specified public choice rather than on fixed-vote recalculations or party advantage

  • A published, reasoned recommendation and a formal government or parliamentary response

    Hypothesis to test

    An accountability output; it does not show which system is better.

  • Readers and voters correctly treat recalculated seat totals as illustrations, not forecasts

    Hypothesis to test

    Voters, parties and turnout would behave differently under other rules; tested through comprehension testing of the site’s illustrations.

Outcomes are kept separate and never added into one impact figure.

5.Best evidence

  • How are MPs elected? and A Royal Commission and two referendums

    Author or institution:
    Electoral Commission (New Zealand)
    Published:
    Pages read via archive copies of December 2025 and January 2026
    Evaluation period:
    1986 to 2023
    Design:
    Official description of the system and the reform route
    Sample or population:
    New Zealand voters and elections
    Effect and uncertainty:
    Two votes; 120 seats usually (123 after 2023 because of overhang); list seats need 5% of the party vote or one electorate seat; Royal Commission 1986; referendums 1992 (84.7% for change) and 1993 (53.9% MMP); retained in 2011 (57.77%).
    Limits:
    Describes design and route, not the effects of MMP on government performance; later reviews recommended changing the threshold.

    Where: How are MPs elected?; A Royal Commission and two referendums; The introduction of MMP. Affiliation is provenance, not proof of quality.

  • Report of the Citizens’ Assembly on Democracy in the UK

    Author or institution:
    Citizens’ Assembly on Democracy in the UK (assembly report)
    Published:
    April 2022
    Evaluation period:
    2021 assembly
    Design:
    Deliberative assembly report
    Sample or population:
    Assembly members selected to reflect the UK population
    Effect and uncertainty:
    Did not consider the best electoral system for MPs and said a future assembly could examine it; members backed more use of deliberative processes (90%) as advice rather than binding decisions (85%).
    Limits:
    Members’ votes, not population opinion; no view on voting systems.

    Where: Report PDF p.12; pp.57 and 59. Affiliation is provenance, not proof of quality.

6.Alternatives, counter-evidence and who loses

Closest feasible alternative
A Speaker’s Conference or an expert commission (as New Zealand’s Royal Commission) instead of a citizens’ assembly.
Strongest counter-evidence
Elected MPs, and voters in a referendum, are the legitimate decision-makers; the 2011 referendum rejected the one alternative offered; an assembly can add delay or be seen as framed towards an outcome.

Source: House of Commons Library, Alternative Vote referendum 2011 (RP11-44)

Distributional effects
Affects every voter; parties that would gain or lose seats under each system have opposing stakes in the outcome.
Main downside
Whoever frames the options shapes the result, and an advisory assembly can be ignored.

The options compared, including current policy

  • Current policy

    Keep first past the post: 650 single-member seats, one vote, largest share wins

    Who is reached
    All voters
    Evidence
    2024 results: large gaps between vote and seat shares; strong constituency link
    Likely outcome and timing
    No change
    Cost and funding
    None
    Main trade-off
    Seat shares can differ widely from vote shares

  • Alternative

    Mixed-member proportional (New Zealand-style): constituency MPs plus list MPs topping parties up to their party-vote share above a threshold

    Who is reached
    All voters
    Evidence
    New Zealand since 1996; Scotland’s similar additional member system
    Likely outcome and timing
    At least one parliament after legislation and boundary work
    Cost and funding
    Administration and boundary costs not established
    Main trade-off
    Larger constituencies or more MPs; coalition government more likely; threshold choice contested

  • Alternative

    Single transferable vote: multi-member constituencies, candidates ranked

    Who is reached
    All voters
    Evidence
    Used in Northern Ireland and Scottish councils
    Likely outcome and timing
    At least one parliament after legislation
    Cost and funding
    Counting and boundary costs not established
    Main trade-off
    Weaker single-MP link; longer counts

  • The proposal

    Citizens’ assembly weighs the three, with a committed response and two-stage referendum route

    Who is reached
    Voters through a representative sample; then everyone at any referendum
    Evidence
    New Zealand route; UK 2021 assembly
    Likely outcome and timing
    Recommendation in about a year
    Cost and funding
    Not costed; no budget identified
    Main trade-off
    Time and framing risk

7.What other countries or the devolved nations show

Country lesson · New Zealand, Royal Commission 1986; referendums 1992 and 1993; first MMP election 1996; retention referendum 2011

Switching from first past the post to mixed-member proportional voting in New Zealand

Evidence: Observational analysisPartial match: some conditions differ

What was changed
Each voter casts an electorate vote (single-member seats, first past the post) and a party vote; list seats top parties up to their party-vote share if they win 5% of party votes or one electorate seat; Parliament usually has 120 seats (123 after 2023 because of overhang).
Study design and population
Description of a reform route and system design; outcomes are observed elections, not a controlled comparison New Zealand voters
Measured outcome there
Route: an independent Royal Commission recommended MMP; an indicative referendum (1992: 84.7% for change, 70.5% for MMP) was followed by a binding one (1993: 53.9% MMP, 46.1% first past the post); voters kept MMP in 2011 (57.77%). Design outcomes since 1996 (coalition or minority governments) are observed but not causally separated from other changes.
Cost status
Costs of the Royal Commission and referendums not taken from a primary source here.
What failed or remains uncertain
Reviews have recommended changing the threshold (to 4% in 2012, 3.5% in 2023) and ending the one-seat rule, which shows the original design had contested features; no evidence was found that the threshold has been changed in law. Voters and parties changed behaviour under the new rules, so pre-reform results were a poor guide to seats.
Why the UK differs
The UK Parliament has 650 seats, a much larger electorate, devolved legislatures already using other systems (the Senedd moves to closed lists in 2026) and a 2011 referendum that rejected the alternative vote.
First change required here
Give an independent body or citizens’ assembly the remit to recommend among fully specified systems, with an indicative-then-binding decision route agreed in advance, as New Zealand did.

Not a UK forecast: the effect above was measured in that place and population. Source: Electoral Commission (New Zealand), How are MPs elected? and A Royal Commission and two referendums (How are MPs elected?; A Royal Commission and two referendums); Independent Electoral Review (New Zealand Ministry of Justice), Independent Electoral Review: Final Report (He Arotake Pōtitanga Motuhake) (Recommendations 7–10). Reviewed 2026-10-04.

8.What delivery needs first

  • law — Any change to the system, and any referendum, needs an Act of Parliament. (Genuine veto: nothing proceeds without it; owner: Parliament)
  • public consent — A referendum result in favour, by the 2011 precedent. (Genuine veto: nothing proceeds without it; owner: Voters)
  • dependency — An agreed remit and balanced evidence panel, accepted across parties before the assembly starts. (Requirement; owner: Commissioning body)

9.What it would cost

How the cost is built up: Assembly (recruitment + member payments + facilitation + evidence + administration) + independent process review; any referendum costed separately by the Electoral Commission.

  • Citizens’ assembly: recruitment, member payments, facilitation, evidence, accessibility and administration

    One national assembly on the Westminster voting system

    Not yet costed (ledger C-A33-ASSEMBLY)

    one-off revenue; price year not stated; About a year; Not yet established

  • Method, peer review and comprehension testing of the site’s systems comparison

    UK Facts

    Not yet costed (ledger C-A34-EDITORIAL)

    one-off revenue; price year not stated; Before the next update; Not yet established

10.Who pays, and what is missing

Programme envelope (a possible route, not an award)
None identified
Allocation committed to this change
None
Remaining gap
No contemporary national price found; the 2021 assembly report does not give its cost.
Proposed financing
A named Cabinet Office or parliamentary commissioning budget; not assumed savings elsewhere.
Responsible payer
central government
Budget displaced
Other Cabinet Office or parliamentary spending.

11.First milestone and time to a useful result

A published remit naming the three options, the evaluation criteria, the evidence-governance arrangements and the commitment on what happens to the recommendation (Owner: UK government or the commissioning Commons committee. Proposed by UK Facts, not an official deadline.)

Time to first useful result: About a year from commissioning to recommendation.

What could delay it: No agreement on the remit across parties Parliamentary time is not available for a response or referendum bill

12.How we would know

Baseline
No UK assembly has examined the Westminster system; current illustrations labelled on this page.
Comparison
The 2021 assembly’s process standards and New Zealand’s route.
Leading indicator
Representativeness of members and balance of evidence, judged by an independent process review.
Follow-up
A published recommendation and a formal, reasoned response within the committed period.
Continue if
The process review finds the remit and evidence balanced and a formal response is made.
Adapt if
The review finds gaps in balance: add evidence sessions before members vote.
Stop if
An independent reviewer finds the remit or evidence unbalanced, or no formal response is made — then treat the assembly as failed, as the action’s own rule states.
Thresholds
Not yet set: A deliberative process; no numerical threshold is justified.

What is not yet known, and how to find out

  • Cost of a national assembly (cost)Next step: Commissioning body to obtain quotes from deliberation organisers.Scope: One national assembly of about a year · Data or quotes needed: Organiser quotes; member payment rates · Who can estimate it: Cabinet Office or the commissioning committee
  • How voters and parties would behave under each system (effect)Next step: Not knowable in advance; present seat calculations only as labelled illustrations and use evidence from systems already used in the UK.Defensible route: further research
  • Which threshold and seat ratio an MMP option should specify (legal)Next step: Give the assembly the options reviewed in New Zealand (5%, 4% and 3.5%; one-seat rule) as explicit choices.

Sources last checked 4 October 2026 · Owner: Evidence editor (James Harris) · Next check: the first trigger: A government or parliamentary decision on a citizens’ assembly or electoral reform.

What it would take

The order things have to happen in, who pays, and the effects and appraisals on record.

The order things have to happen in

  1. First, the prerequisite

    Publish a bounded, peer-reviewed comparison of systems

    Owner: UK Facts (this page)

    No date: the timing depends on the steps before it.

  2. Then, the decision

    Decide whether to commission an assembly, and agree its remit and the response route

    Owner: UK Government or Commons committees

    No date: the timing depends on the steps before it.

  3. Then, delivery

    Run the assembly with balanced evidence

    Owner: Independent organiser

    No date: the timing depends on the steps before it.

  4. Finally, the measured outcome

    A published recommendation and a formal response; any change by Act of Parliament and referendum

    Owner: Parliament

    No date: the timing depends on the steps before it.

Who pays, and what is still missing

Cost, committed funding and the remaining gap for the same scope and years. A programme envelope is not an award to a project; a proposal is not committed money. None of these costs has been established yet, so no total is shown.

Cost and funding ledger

  • Citizens’ assembly on the Westminster voting system

    A33 · administration · not costed

    Amount
    Not yet costed
    Who pays
    central government
    Committed
    None identified
    Proposed, not committed
    —
    Gap
    Not established

  • Method, peer review and comprehension testing of the systems comparison

    A34 · private contribution · not costed

    Amount
    Not yet costed
    Who pays
    UK Facts
    Committed
    None identified
    Proposed, not committed
    —
    Gap
    Not established

“Not yet costed” means no defensible cost has been found — not that the action is free. Lifetime benefits, benefit-cost ratios and forecast savings are never shown here as money available to spend.

What the evidence says each action changes

No effect has been established for these actions yet: direction plausible; size not established.

How we would know

Gallagher index of disproportionality, general election; MPs elected with under half their constituency vote; Formal response to a deliberative process on the voting system.

The outcome measures to watch. A baseline is where we start, not a target; where there is no official target we say so.

  • Gallagher index of disproportionality, general election

    index (0 = seats match votes) · United Kingdom

    Baseline
    Not published
    Latest
    23.8
    4 July 2024

    Target: none — how much proportionality is right is a political choice, traded against other aims.

    Source: House of Commons Library, General election 2024 results (CBP-10009) (Full-detail 2024 results (site calculation)). Next release: the next general election (check the release calendar).

  • MPs elected with under half their constituency vote

    of 650 seats · United Kingdom

    Baseline
    Not published
    Latest
    554 of 650
    4 July 2024

    Target: none — a description of how the system works, not a target.

    Source: House of Commons Library, General election 2024 results (CBP-10009) (Constituency results (site calculation)). Next release: the next general election (check the release calendar).

  • Formal response to a deliberative process on the voting system

    published response · United Kingdom

    Baseline
    Not published
    Latest
    Not published

    Target: none — no assembly on the voting system has been commissioned.

    Source: UCL Constitution Unit, Report of the Citizens’ Assembly on Democracy in the UK (Report PDF p.12 (question left for a future assembly)). Next release: only if an assembly is commissioned (check the release calendar).

Where the ideas come from

Research, counter-evidence and methods (8 sources; 3 claims held back)
  • General election 2024 results (CBP-10009) — House of Commons Library, 3 March 2026 (dataset revision; record of dataset changes updated 5 January 2026).Official election results (research briefing and data); United Kingdom. Relevant passages checked (Data ingested into the site by scripts/ingest-elections.py; the live page returned HTTP 403 to automated checks on 4 October 2026.), 2026-10-04.
  • Senedd Cymru (Members and Elections) Act 2024: explanatory notes — legislation.gov.uk, 2024.Legislation (explanatory notes); Wales. Relevant passages checked, 2026-10-04.
  • Electoral systems across the UK (SN04458) — House of Commons Library, Updated 23 June 2026.Research briefing; United Kingdom. Relevant passages checked (Live page returned HTTP 403 to automated checks on 4 October 2026; used for definitions only.), 2026-10-04.
  • How voters found the May 2026 elections in England — Electoral Commission, date not stated.Regulator research; England. Relevant passages checked, 2026-10-07.
  • General election results from 1918 to 2019 (CBP-8647) — House of Commons Library, date not stated.Official election results (research briefing and data); United Kingdom. Relevant passages checked (Data ingested into the site; the live page returned HTTP 403 to automated checks on 4 October 2026.), 2026-10-04.
  • Report of the Citizens’ Assembly on Democracy in the UK — UCL Constitution Unit (Alan Renwick, Kaela Scott, Meg Russell, James Cleaver, Frances Osborne (UCL Constitution Unit and Involve)), 2022-04.Deliberative mini-public: members’ conclusions after evidence and deliberation; 67 members recruited to be representative of the UK adult population; United Kingdom. Relevant passages checked (read from an Internet Archive copy), 2026-10-04. Limits: Explicitly did not consider the best electoral system for MPs (PDF p.12), so it is evidence on deliberative process only, never on voting systems. Percentages are members’ votes, not population opinion.
  • The path to net zero (final report) — Climate Assembly UK, September 2020.Citizens’ assembly report; United Kingdom. Relevant passages checked, 2026-10-04.
  • Alternative Vote referendum 2011 (RP11-44) — House of Commons Library, 2011.Research paper (referendum result); United Kingdom. Relevant passages checked (Live page returned HTTP 403 to automated checks on 4 October 2026; cited for the fact of the 2011 result only, with no figures repeated here.), 2026-10-04.

Counter-evidence and criticism

  • Give electoral reform an informed public decision process: Elected MPs, and voters in a referendum, are the legitimate decision-makers; the 2011 referendum rejected the one alternative offered, and an assembly can add delay or be seen as framed towards an outcome. (House of Commons Library)
  • Compare voting systems without pretending votes stay unchanged: Any recalculation invites misuse: even a labelled illustration frames the debate around seat counts and can be read as a prediction.

Claims held back

  • That a citizens’ assembly would favour any particular voting system — The 2021 assembly explicitly did not consider electoral systems; its members’ views on other questions are not evidence on this one. Needed: An assembly that actually examines the question.
  • The cost of a national citizens’ assembly on the voting system — No contemporary published cost was found; the 2021 report does not state one. Needed: A specified remit and budget.
  • Seat totals under another system presented as what “would have happened” — Voters, parties and turnout would change under different rules; no source can observe that. Needed: Not releasable as a forecast; illustrations stay labelled as such.

“Full text checked” means we read the report itself; “relevant passages” means the sections behind each figure; “summary or abstract only” means we could not read the full study, so no number from it is published here without another source.

Other options compared — not on the shortlist (4)

Other options compared

Options from earlier work on this page that are not on the shortlist. They remain valid choices; their evidence is shown as before.

  • structuralStatus: operating

    Keep First Past the Post

    Aims to:
    Retain single-member constituencies and decisive single-party majorities from the 2024 baseline.
    How:
    No change to the rules. One MP per constituency; the candidate with most votes wins.
    Who decides:
    UK Government and Parliament (no decision required to continue).
    Main constraint:
    The gap between votes and seats is likely to persist while support is spread across more than two parties.
    Evidence:
    Moderate evidence — evaluated, with limits on scope or transfer
    See the trade-offs and evidence
    What the evidence shows
    The system’s observed effects are well documented in UK results: it usually produces single-party majorities (VOTE-05) and large votes–seats gaps when voters spread across parties (VOTE-04). Whether those effects are desirable is a value judgement, not an evidence question.
    Resources
    None beyond existing election administration.
    Consent and decisions needed
    No new decision is needed. Public support for the current system relative to alternatives is not measured on this page; the last direct test was the 2011 referendum.
    Time
    Immediate — it is the current system.
    Cost and yield
    No additional cost.
    Trade-offs and who pays
    Keeps the constituency link and a clear route to single-party government; keeps large differences between vote and seat shares for parties with spread-out support.
    How we would know it worked
    Leading indicator: Constituency results continue to produce a governing majority. Outcome: Turnout and confidence in elections, tracked separately from proportionality. It would not be working if: Repeated hung parliaments would remove the main claimed advantage.
  • structuralStatus: external option

    Alternative Vote (ranked ballot, single-member seats)

    Aims to:
    Each MP elected with majority support after preferences are counted; constituency link kept.
    How:
    Voters rank candidates. If no one has over half the first preferences, the last-placed candidate is eliminated and their votes transferred until one candidate passes 50%.
    Who decides:
    UK Government (bill), Parliament (Act); Electoral Commission (referendum oversight and voter information).
    Main constraint:
    The 2011 referendum result is the most recent public decision on this question.
    Evidence:
    Limited evidence — plausible mechanism, little direct evaluation
    See the trade-offs and evidence
    What the evidence shows
    Put to a UK referendum on 5 May 2011 and rejected: 67.9% voted No on a 42.2% turnout. AV is not a proportional system and can produce large votes–seats gaps; it mainly removes the incentive to vote tactically within a seat. No UK evaluation of its effect on outcomes exists.
    Policy status
    Rejected at referendum in 2011; no party currently proposes it for the Commons as its preferred system.
    Resources
    New ballot papers, longer counts, voter information campaign.
    Consent and decisions needed
    An Act of Parliament; by the 2011 precedent, a referendum.
    Time
    Several years: legislation, then a first election under the new rules.
    Cost and yield
    No official costing on this page.
    Trade-offs and who pays
    Keeps single-member seats; does little for proportionality; counts take longer.
    How we would know it worked
    Leading indicator: Share of MPs elected with over 50% after transfers. Outcome: Fewer voters reporting a tactical rather than sincere vote (survey measure). It would not be working if: Votes–seats gaps no smaller than under FPTP and no reduction in tactical voting.
  • structuralStatus: external option

    Additional member system (constituency MPs plus regional top-ups)

    Aims to:
    Seat shares closer to vote shares while keeping constituency MPs.
    How:
    Two votes: one for a constituency MP elected by FPTP, one for a party list. Regional list seats are allocated to bring each region’s result closer to the list vote.
    Who decides:
    UK Government and Parliament; Boundary Commissions (fewer, larger constituencies or a larger chamber).
    Main constraint:
    Either constituencies grow or the chamber grows (chapter 4 shows the top-ups grow with the skew); two classes of MP.
    Evidence:
    Moderate evidence — evaluated, with limits on scope or transfer
    See the trade-offs and evidence
    What the evidence shows
    Used for the Scottish Parliament since 1999 and for Senedd elections from 1999 to 2021; both have produced coalition or minority governments as well as one Scottish majority. Evidence on outcomes comes from these UK uses; transfer to a 650-seat Commons is untested. The single-vote illustration in chapter 4 understates real design choices.
    Resources
    Boundary review for fewer constituencies or more seats; new ballot design; voter information.
    Consent and decisions needed
    An Act of Parliament and probably a referendum.
    Time
    A boundary review alone takes years; first election under new rules unlikely within one Parliament.
    Cost and yield
    No official costing on this page.
    Trade-offs and who pays
    More proportional; larger constituencies or chamber; coalition or minority government more common.
    How we would know it worked
    Leading indicator: Gallagher index at the first election under the new rules. Outcome: Proportionality improves without a fall in turnout. It would not be working if: Disproportionality not materially lower than under FPTP.
  • structuralStatus: proposed

    Single Transferable Vote in multi-member constituencies

    Aims to:
    Proportional results with ranked choice of individual candidates.
    How:
    Larger constituencies elect several MPs; voters rank candidates; candidates reaching a quota are elected and surplus or eliminated votes transfer by preference.
    Who decides:
    UK Government and Parliament; Boundary Commissions; returning officers.
    Main constraint:
    Single-member constituency link replaced by shared representation; counts more complex.
    Evidence:
    Moderate evidence — evaluated, with limits on scope or transfer
    See the trade-offs and evidence
    What the evidence shows
    Used in the UK for the Northern Ireland Assembly and for local councils in Northern Ireland and Scotland (since 2007). Liberal Democrat policy for the Commons. UK experience shows it working at Assembly and council scale; no evaluation exists for a Westminster-sized chamber.
    Policy status
    Party policy of the Liberal Democrats (see chapter 6); not government policy.
    Resources
    New multi-member boundaries, counting systems that handle transfers, voter information.
    Consent and decisions needed
    An Act of Parliament and probably a referendum.
    Time
    Several years including boundary design.
    Cost and yield
    No official costing on this page.
    Trade-offs and who pays
    More proportional and candidate-centred; larger seats; coalition or minority government more common.
    How we would know it worked
    Leading indicator: Share of first preferences that help elect someone after transfers. Outcome: Proportionality and turnout at the first STV election, reported separately. It would not be working if: High ballot spoilage or lower turnout without gains in proportionality.
The options side by side
OptionResourcesTimeEvidenceOutcome to watch
Keep First Past the PostNone beyond existing election administration.Immediate — it is the current system.moderateTurnout and confidence in elections, tracked separately from proportionality.
Alternative Vote (ranked ballot, single-member seats)New ballot papers, longer counts, voter information campaign.Several years: legislation, then a first election under the new rules.limitedFewer voters reporting a tactical rather than sincere vote (survey measure).
Additional member system (constituency MPs plus regional top-ups)Boundary review for fewer constituencies or more seats; new ballot design; voter information.A boundary review alone takes years; first election under new rules unlikely within one Parliament.moderateProportionality improves without a fall in turnout.
Single Transferable Vote in multi-member constituenciesNew multi-member boundaries, counting systems that handle transfers, voter information.Several years including boundary design.moderateProportionality and turnout at the first STV election, reported separately.

Plan reviewed 2026-10-04. How we judge evidence.

How this connects

Related: elections and key dates.

Sources and methods (6)

Method notes

  • Gallagher index: √(½ × Σ(Vᵢ − Sᵢ)²), with vote and seat shares in percentage points. It depends on how finely parties are grouped, so the long-run series uses the same five groups for every year, and the full-detail 2024 value is reported separately.
  • Effective number of parties (Laakso–Taagepera): 1 ÷ Σ(sᵢ²), shares as fractions; computed on votes and on seats.
  • Allocation illustrations (chapter 4) apply a named formula to the actual 2024 votes as if the UK were one constituency. They are not forecasts: under different rules voters, parties and tactical choices would change.
  • Winning-share and margin bands are conventions chosen by this site, not official categories. “Electorate” means registered electors.
  • Reconciliation: the 2024 party rows sum to 28,809,340 valid votes and 650 seats, against published totals of 28,809,340 and 650.