What is proportional representation?

Proportional representation, or PR, is a type of voting system where parties win seats roughly in proportion to their share of the vote. If a party wins 20% of the votes, it gets around 20% of the seats. The Scottish Parliament, Senedd and Northern Ireland Assembly use PR, but Westminster does not.

There are several kinds of PR. In list systems, voters choose a party and seats are filled from party lists. The Senedd moved to a closed list system in 2026. The single transferable vote lets voters rank candidates in multi-member areas, and is used in Northern Ireland. Mixed systems, such as the additional member system, combine local members with top-up seats.

Westminster uses first past the post, where the candidate with the most votes in each seat wins. This can produce big gaps between votes and seats. In 2024, Labour won about 63% of seats on about 34% of the vote. Reform UK won 14% of the vote but only five seats. The Liberal Democrats and Greens also won far fewer seats than their vote shares would suggest under a proportional system.

Supporters say PR is fairer, gives smaller parties a voice and makes every vote count. Critics say it weakens the local link between MP and voters, produces coalitions decided after the election, and can give small parties outsized influence. In 2011 the UK rejected a move to the alternative vote, which is not itself proportional, by 68% to 32% in a referendum.