Last year’s General Election was the most disproportionate in British electoral history. Labour won 63% of MPs on just 34% of the vote. On one measure of disproportionality, the Gallagher Index, which measures the gap between the vote shares and seat shares of all the parties in an election, the 2024 election scored 23.6. The previous high was 20.6 in 1983; the highest current Gallagher Index score globally is 29 in Saint Lucia.

The disproportionality of the Westminster electoral system results from two factors: First past the post voting and the fragmentation of the British party system, with up to six competitive parties depending on which part of the UK we examine. Labour’s majority in the Commons is built on many narrow wins with a minority of the vote, with the opposition to Labour split across multiple parties. As a result, according to the Electoral Reform Society, 16.6 million voters are now "unrepresented", a majority of voters.

Under more proportional electoral systems, the Commons would much more closely reflect how Britain actually voted in July. The single transferable vote system used in Scottish local elections would have seen Labour win 35% of seats, much closer to their actual vote share. An Additional Member System, like the one we use at Holyrood, would have had Labour winning 43% of seats.

But it’s not just the Westminster electoral system that’s creaking under the strain of our fragmented party system. With the rise of Reform UK north of the Border as well as south of it, we are poised to have the most disproportionate Holyrood election ever next year.

Currently, the

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