Proportional representation

If first-past-the-post is the simplest way to turn votes into seats, proportional representation (PR) is the family of systems built around a different goal: making a parliament look like the electorate that chose it. Under PR, a party that wins a quarter of the votes should win roughly a quarter of the seats. That single principle reshapes everything downstream — how many parties thrive, how governments are formed and how strong the link between a voter and a named representative remains. The UK already uses several PR systems for its devolved and local elections, even as it keeps FPTP for the House of Commons.

What “proportional” actually means

Under FPTP, the candidate with the most votes in each single-member constituency wins, and the largest party typically gets a seat share well above its vote share. PR systems are engineered to close that gap. They do so by using multi-member districts (where several representatives are elected together) or top-up seats that correct imbalances. The practical effect is that smaller parties with broad but thin support — penalised heavily under FPTP — win seats roughly in line with their votes, and very few votes are “wasted” on losing candidates.

There is no single PR system; the label covers a spectrum. The three that matter most for the UK are party-list PR, the Single Transferable Vote and the Additional Member System.

Party-list PR

In party-list PR, parties put forward lists of candidates in multi-member areas, and seats are shared out in proportion to each party’s vote. Win 30% of the vote and you take about 30% of the seats. The key variant is whether the list is closed or open. With a closed list, the party fixes the running order, so voters pick a party but not which of its candidates are elected. With an open list, voters can express a preference among a party’s candidates, giving them a say over individuals. Party-list systems are among the most directly proportional, but pure closed lists are often criticised for weakening the personal link between voters and a named representative.

The Single Transferable Vote

The Single Transferable Vote (STV) works in multi-member constituencies where voters rank candidates in order of preference. A candidate who reaches a set quota is elected; any surplus votes beyond the quota, and the votes of eliminated candidates, are transferred according to the next preferences marked. The result is broadly proportional while still letting voters choose between individual candidates — including rival candidates of the same party. In the UK, STV is used for the Northern Ireland Assembly and councils, and for Scottish local elections, where the ability to express cross-cutting preferences is especially valued.

The Additional Member System

The Additional Member System (AMS) is a mixed system that tries to combine a local MP with overall proportionality. Each voter casts two votes: one for a constituency representative elected by FPTP, and one for a party across a wider region. The regional “top-up” seats are then allocated to compensate parties that did badly in the constituency contests, pulling the overall result back towards proportionality. AMS is used for the Scottish Parliament and the Senedd. Voters keep a recognisable constituency member while the list seats correct the distortions of the first-past-the-post element.

Consequences and the balanced debate

Because PR makes seats track votes, it is much harder for one party to win an outright majority of seats on a minority of votes. The usual result is coalition or minority government, with parties bargaining to form an administration. Some PR systems use a threshold — a minimum vote share, such as 5% — to keep tiny or fragmentary parties out, trading a little proportionality for stability.

Supporters of PR argue that it is simply fairer: seats reflect votes, fewer votes are wasted, smaller parties with genuine national support are represented, there are fewer “safe seats”, and government by negotiation can build broader consensus. Supporters of FPTP counter that PR can weaken the single-MP constituency link (particularly under closed lists), produce slower or less stable coalition bargaining, and hand small parties outsized leverage as “kingmakers” in coalition talks. They value the decisive, accountable single-party government that FPTP tends to deliver.

It is worth noting what PR is not. The Alternative Vote, rejected by UK voters in the 2011 referendum, is a majoritarian single-member system: it redistributes preferences to find a majority winner in each seat but does not aim to make the overall seat total proportional. PR, by contrast, is defined precisely by that proportional aim. Reform campaigners such as the Electoral Reform Society advocate for PR; neutral bodies like the Electoral Commission and UK Parliament describe how each system works without taking sides.