Some results in local council and devolved elections this week can be forecast with confidence, but none with precision. Labour will have a torrid time everywhere. Reform UK will do well, continuing the trend of recent years. The Greens will surge in parts of London. Plaid Cymru will enjoy a breakthrough in Wales. Those trends could produce a wide spectrum of outcomes in terms of seats on councils and in the Scottish and Welsh parliaments. Much depends on the way that tight races involving many parties are filtered through different electoral systems.

The first-past-the-post model used to elect local authorities in England is ill-suited to multiparty politics. It was already flawed in the era when political competition was defined by the rivalry between Labour and the Conservatives. Smaller parties were locked out. Too many voters felt their ballots counted for nothing in safe seats.

But there is an additional perversity when four or five parties have poll ratings somewhere between the high teens and high twenties. The threshold for victory drops. The winning candidate might have been opposed by a clear majority. The average winner’s vote share in last year’s local elections was 40.7% – the lowest on record. About 75 candidates were elected on vote shares lower than 30%.

Scottish councils (not up for election this year) work around this problem by using the single transferable vote system. Voters rank candidates in order of preference. Seats are awarded by eliminating the least popular candidates. The devolved parliaments in Edinburgh and Cardiff are both elected on different systems. Each is designed to express the balance of opinion more fairly. Neither is flawless. In Scotland, the combination of constituency ballots and regional “top-up” lists creates different categories of MSP and introduces a layer of complexity that turns tactical voting into a game of second-guessing the way parallel ballots might play out.

The Welsh Senedd will this year try a new “closed proportional list” system. Voters choose a party, represented on the ballot paper by a bloc of candidates. Seats are then allocated on a proportional basis within large, six-member constituencies. In theory, this ensures a broadly representative chamber, although it could exclude a party that wins a modest but not tiny vote share. It sets a prohibitive threshold for independents to reach the Senedd. Closed lists also prevent voters rewarding an exceptional individual candidate from a party that they would otherwise not endorse.

No electoral system is perfect. Fairness can be variously defined as a balance between proportionality or constituency link. The relative merits of the different models in operation this week are unlikely to be a prominent feature of post-election debate. Attention will naturally be more focused on Labour’s collapse, Plaid Cymru and Reform UK potentially dominating in Wales, the Scottish National party defying gravity to keep power in Scotland, for example, and not the psephological mechanics that generated those outcomes.

But there must come a time to address the question of how Britain’s fragmented political allegiances can best be turned into fair parliamentary representation. The current arrangement is plainly unsuitable. In 2024, Labour won a huge Commons majority with barely more than a third of national votes cast. It was a brittle kind of victory. The result of the next election could look downright perverse if the current trend of close, multiparty competition is sustained. The contours of politics are in flux. An electoral system that looks incapable of reflecting that change undermines the integrity of British democracy.

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