The political landscape in Wales—and, by extension, the United Kingdom—is shifting in ways few could have anticipated just a few years ago. The recent Caerphilly Senedd byelection, held on October 23, 2025, has become a touchstone for these changes, revealing not only the limits of polling but also the evolving nature of voter identity and tactical behavior. The contest, which saw Plaid Cymru surge to victory and Reform UK fall short of expectations, has prompted a wave of analysis, soul-searching, and speculation about the future of Welsh and British politics.
Before the votes were cast in Caerphilly, a Survation telephone poll predicted a very different outcome: Reform UK was expected to win with 42%, while Plaid Cymru was forecast to come in second at 38%. Labour, long the dominant force in the area, was predicted to capture 12%. But when the ballots were counted, the reality was starkly different. Plaid Cymru topped the poll with 47%, Reform trailed at 36%, and Labour managed just 11%. The Conservatives and Greens performed even worse than anticipated, securing 2% and 1.5% respectively, while the Liberal Democrats garnered just 1% (as reported by The Conversation).
This gap between polling and reality has reignited debate about the reliability of constituency-level polling, especially when conducted by telephone. According to The Conversation, national polls tend to be more accurate than those focused on individual constituencies, primarily because it’s more difficult to achieve a representative sample at the local level. The low response rate to telephone polls only compounds the problem.
But the story of Caerphilly isn’t just about polling errors—it’s about identity. Census data from 2021 revealed that 69% of Caerphilly’s population identified as Welsh, significantly higher than the 55% for Wales as a whole. Only 14% identified as British (compared to 18% in Wales), and a mere 4% saw themselves as English (versus 9% in Wales). This matters because, as The Conversation points out, Reform UK’s support is closely tied to English national identity. Across England, the more people identify as English, the more likely they are to vote Reform. In Caerphilly, with its strong Welsh identity and low English identification, Reform struggled to reach the heights predicted by the polls.
This dynamic is not unique to Wales. As noted by columnist Mark McGeoghegan in The Herald, similar forces are at work in Scotland. There, Reform UK is now polling second behind the SNP, ahead of Labour. The rise of Reform is forcing voters to make new tactical choices—sometimes supporting parties they might not otherwise back, simply to keep out the ones they fear most. In Caerphilly, two-fifths of Labour voters from the July 2025 general election supported Plaid Cymru’s Lindsay Whittle in the byelection, many explicitly to prevent a Reform victory. One voter told Whittle, “I don’t want to allow Reform in, but the party that represents my interest most is the Green Party.” After a brief conversation about Plaid’s green credentials, she concluded, “my plan is to vote for you, just definitely not Reform.” (New Statesman, as cited by The Herald).
The polarization between Plaid and Reform was evident not just at the ballot box but in the community. At a town hall debate, local resident Alison Vyas confronted Reform’s candidate Llŷr Powell, saying Reform had made her family “never feel so unwelcome in our own hometown,” and directly blaming Powell for that atmosphere. The comment reportedly drew rapturous applause, highlighting the deep divisions and anxieties at play.
Labour’s collapse in Caerphilly is emblematic of a broader malaise. Having held the seat since the Senedd’s creation in 1999—and in a region where Labour had won every general election since 1918—the party’s third-place finish was a dramatic reversal. Nationally, Labour’s fortunes are also faltering. A YouGov poll from October 30, 2025, placed Labour at just 17% across Great Britain, its lowest ever, and at 14% in Wales ahead of the crucial May 2026 Senedd elections. In Wales, Plaid Cymru and Reform UK are now neck-and-neck, with Labour trailing in third.
As the next round of elections approaches, the rules of the game are changing. The May 2026 Senedd elections will use a new proportional representation (PR) system, increasing the number of members from 60 to 96. Voters will choose closed lists of party candidates in 16 larger constituencies, with six members elected per constituency using the D’Hondt formula. Mark Drakeford, the former First Minister of Wales, has been a vocal advocate for the new system, arguing that it “guarantees a greater sense of continuity than if we were facing an election under our current system, where it’s very likely a Reform insurgent party would take a whole swathe of the 40 first past the post seats on 32% of the vote – and we are mercifully defended against that.” (Labour podcast with Lee Walters).
Drakeford contends that the new system will “guarantee a progressive government in Wales after the election because we will have a system where if 30% of the population in Wales vote for a party of the far right, you’ll have 30% of the votes in the Senedd. 70% of votes will continue to be parties who broadly share a progressive idea of what the future of Wales should be like.”
Reform UK leader Nigel Farage, however, sees things differently. After the Caerphilly byelection, Farage argued that the new system could still work in his party’s favor. “They’ll be fought under D'Hondt. If that result was repeated across Caerphilly and Blaenau next year, there’d be three Plaid members and three Reform members. So I can’t be disappointed by that in any way at all. We’re cracking on.” (ITV Cymru Wales/Barn Cymru poll analysis).
Indeed, the latest Wales-wide polling suggests that Reform UK could win a substantial number of seats under the new system, with Plaid Cymru and Reform nearly tied and Labour lagging far behind. No party is projected to win a majority, making post-election coalitions almost inevitable.
Reform UK’s Wales spokesperson took aim at Labour and Plaid Cymru, accusing them of “redrawing of the electoral map” to benefit the political establishment and warning that “the choice for Wales will be between Plaid Cymru, who supported these changes to the electoral system, or Reform, who are fighting to give a voice to the voiceless here in Wales.”
Meanwhile, in Scotland, the rise of Reform is also shaking up old assumptions. Tactical voting, which had historically allowed unionist parties to hold off the SNP in key constituencies, is now being tested by a new three-way competition among SNP, Reform, and either Labour or the Conservatives. As McGeoghegan notes, “next May’s election will be defined by the question of who voters want to keep out, not who they want to govern.”
This moment marks a profound realignment in British politics. The emergence of multi-party competition, the role of national identity, and the introduction of new electoral systems are all contributing to an unpredictable and dynamic environment. For voters and parties alike, the old certainties are gone. The only thing that seems certain now is change itself.
