How Do UK Voting Systems Work—and What Would Proportional Representation Change?
Summary: This guide breaks down how FPTP, AMS, STV, and party-list voting operate in the UK, and what a switch to proportional representation at Westminster would change.
The UK runs elections on several different systems, not one. They divide into two families: plurality/majoritarian rules, where the winner takes the seat, and proportional rules, where a party's seat share is meant to track its vote share. Politics.co.uk offers a clear map of the main variants, from first past the post to the hybrid systems used in devolved parliaments.
First Past the Post
FPTP remains the system for the House of Commons. The UK is carved into 650 constituencies, each with a roughly similar number of voters. Candidates compete for a single seat, and voters make one X on the ballot. The candidate with the most votes takes the seat, no majority required.
Backers value its simplicity and its tendency to produce single-party majority governments. Critics call it distortive. The 2024 general election gave its critics ammunition: a party won a large Commons majority on 33.7% of the national vote, while Reform UK took 14.3% of the national vote and only five seats. Politics.co.uk reports that about 58% of voters in that election backed candidates who lost, the highest share of unrepresented votes on record.
AMS: Two Votes, Two Effects
The Additional Member System tries to soften FPTP's rough edges. Voters get two ballots: one for a constituency MP or MSP, decided by FPTP, and a second for a party in a larger region. The regional seats top up the result so the chamber roughly reflects the party vote. The Scottish Parliament works this way, electing 73 constituency MSPs and 56 regional members.
STV and Party Lists
The Single Transferable Vote takes a different approach. It is both proportional and preferential. Multi-member constituencies elect several representatives at once, and voters rank candidates 1, 2, 3 and so on. To win, a candidate must pass a quota calculated using the Droop formula. Surplus votes move on, which means voters can choose between individual candidates from the same party as well as between parties.
Party-list systems are plainer. Voters choose a party, parties publish ranked lists, and seats are allocated according to the party's share of the vote in a multi-member area.
What a Switch Would Change
Introducing a proportional system for Westminster would change more than the maths. Single-party majorities usually rest on FPTP's winner-take-all effect. Under AMS, STV, or a party list, coalitions and negotiated policy packages would become the norm rather than the exception.
The idea is already part of the political conversation in Britain. Andy Burnham, the Mayor of Greater Manchester, used his Labour conference speech to call for the next Labour manifesto to commit to changing the Westminster voting system. The BBC reports that he plans to fight the next election on that pledge; the Guardian says he is expected to push ahead with electoral reform. Burnham also raised a closer relationship with the European Union after a review.
Which model might actually replace FPTP has not been settled. AMS, STV, and party lists each involve trade-offs between proportionality, local links, and simple ballot papers. After the 2024 election, YouGov polling found 49% of the public backed a more proportional system and 26% favoured keeping FPTP. The argument is no longer abstract.