How Proportional Voting Could Reshape Britain’s Parliament

New modelling by More in Common compares FPTP with three proportional alternatives: regional party list, the additional member system (AMS) and single transferable vote (STV). Using the latest average of ten opinion polls, Reform UK would secure 46 % of seats under FPTP despite winning 28 % of the vote. Under a regional party list Reform would receive roughly 28 % of seats; AMS about 33 %; and STV around 27 %.

The Guardian

The Greens, who hold no seats under FPTP, would gain at least four seats under any PR model. In London Labour’s share would fall from 64 % of seats under FPTP to no more than 40 % under the three proportional systems, while Reform and the Greens would increase their representation. In the North-East Reform’s projected share would drop from 85 % of seats under FPTP to 51 % under AMS, 33 % under a party list and 30 % under STV.

The Guardian

All scenarios produce a parliament without a single-party majority, making a coalition—either a progressive alliance of Labour, the Liberal Democrats, the Greens, the SNP and Plaid Cymru, or a Reform-Conservative partnership—the only viable path to government.

The Guardian

Britain’s electoral map is shaped by FPTP, which translates modest vote shares into disproportionate seat totals. Recent polling shows a fragmented party landscape: Reform UK leads at an average of 26 % support, while the Conservatives and Labour each sit at about 20 %; the Greens and Liberal Democrats follow at 14 % and 12 % respectively. The last general election gave Labour 411 of 650 seats with only 34 % of the popular vote, underscoring how small vote-share shifts can produce large swings in parliamentary composition.

The Guardian

Incoming prime minister Andy Burnham has publicly endorsed proportional representation, joining calls from Labour figures, the Liberal Democrats, the Greens, the SNP and Plaid Cymru for reform.

The Guardian

Prime Minister Andy Burnham told the *Observer* that he is “committed to proportional representation” and believes it would “change the political culture.”

The Guardian

Darren Hughes, chief executive of the Electoral Reform Society, warned that any move toward PR would likely require a national referendum, citing the 2011 vote on the alternative-vote system, which was rejected.

The Guardian

Analysts note that voter behaviour under a new system is uncertain. The modelling assumes current polling patterns will persist, but a shift to proportional voting could alter strategic voting and party tactics. The cost of securing a seat varies dramatically: a Green seat would require roughly 280,000 votes, whereas a Reform seat would need about 26,000 votes under the latest model.

The Guardian

The projections rely on aggregated polling data, which may change in the weeks leading up to a future election. No source provides definitive forecasts of how voter turnout or party campaigning would adapt to a proportional framework, leaving a gap in understanding the practical implications of such a transition.

The Guardian

Experts agree that any substantive alteration to the Westminster voting system would almost certainly trigger a referendum, given the constitutional significance of the change. Should a referendum be called, the outcome would determine whether Britain adopts a more proportional map and how the balance of power among parties evolves for years to come.

The Guardian