Victory for Plaid Cymru and a strong second-place finish for Reform UK in last week’s Caerphilly by-election is being viewed as further evidence that Britain is entering a new era of multi-party politics.
For the headline writers, Reform’s 36% vote share in the poll for a Senedd seat confirmed that the insurgent force is maintaining momentum and threatening to seriously challenge both Labour and the Conservatives across the regions and nations of the UK at the next general election.
Yet Nigel Farage and his team, who had made clear their confidence of winning the contest, were frustrated at being beaten by the left-leaning Plaid. And the result may also fuel suspicions that Reform’s support base is broad but too shallow to translate into an electoral landslide.
Westminster’s first-past-the-post (FPTP) voting system has always been brutal for parties with broad but thinly spread support. In 2015, UKIP won nearly four million votes (12.6%) and returned just one MP. The SDP–Liberal Alliance in the 1980s twice took over 22% of the national vote in general elections yet barely scraped a few dozen seats. And even Reform’s 2024 result – 14% of votes, five MPs – stands as one of the most lopsided outcomes in modern British politics.
The problem is down to the geography of the electoral map. Labour and the Conservatives traditionally had strongholds where concentrated support turned votes into Commons seats. Reform, by contrast, polls well almost everywhere but rarely dominates any single seat. Under FPTP, finishing second counts for nothing.
Caerphilly’s result, under a different voting system to Westminster, shows Reform can push the main parties hard. But without concentrated support in winnable constituencies, Reform’s national vote share risks being politically inefficient in terms of seats gained.
Predicting the result of a general election that is still almost certainly well over three years away is a fool’s errand.
At the 2015 general election, UKIP won millions of voters, one Commons seat and a place in the record books as the most under-represented party in modern political history. Given FPTP’s knack of thwarting parties that seek to break the Westminster mould, the risk for Reform is that it is doomed to match that unenviable record.
