After more than a century of Labour dominance in Caerphilly, the political map of Wales shifted dramatically on October 24, 2025. Plaid Cymru’s Lindsay Whittle clinched a landmark victory in the Senedd by-election, ending Labour’s unbroken grip on the area and sending shockwaves through the Welsh and UK political establishment. For the first time in 100 years, Labour failed to secure the seat, attracting a mere 11% of the vote. The Conservatives fared even worse, scraping just 2%. Together, these two parties—the traditional titans of Westminster—accounted for only 13% of ballots cast, a figure almost unthinkable in this heartland of Labour history, as reported by BBC.
The contest, however, was far from a straightforward two-horse race. Instead, Plaid Cymru and Reform UK, a relative newcomer on the political scene, dominated proceedings, together capturing 83% of the vote. Plaid Cymru emerged decisively on top, while Reform UK secured a solid second place with 36%, a dramatic increase from its 2% showing in the 2021 election. According to BBC, this surge for Reform UK was impressive but ultimately insufficient, as Plaid’s message resonated more deeply with voters seeking change.
Lindsay Whittle’s victory is as much a personal triumph as it is a political one. A Plaid Cymru councillor for nearly half a century, Whittle had stood for election to Westminster ten times and repeatedly sought office in Cardiff Bay, always finishing second. Now in his 70s, Whittle finally tasted victory. He recalled to BBC, “I remember standing in the crowds in Caerphilly in 1968 as a 15-year-old new recruit to the party.” For decades, defeat at Labour’s hands was a familiar refrain, but not anymore. His perseverance and long-standing commitment to Plaid Cymru have become a symbol of the party’s resurgence and determination to break Labour’s historic hold.
Plaid Cymru’s campaign was carefully calibrated to appeal to a broad cross-section of voters. Under the leadership of Rhun ap Iorwerth, the party deliberately set aside the potentially divisive issue of Welsh independence, promising instead to publish a plan for independence—but not within the first term of a Plaid-led government. The focus, instead, was on bread-and-butter issues: securing a better funding deal for Wales from Westminster, creating jobs, and improving healthcare. As BBC noted, “Plaid Cymru successfully presented itself as the vehicle for change from a deeply unpopular Labour UK government and a Welsh Labour party that's been ruling the roost since Tony Blair's landslide victory in 1997.”
This pragmatic approach paid off handsomely. Plaid Cymru managed to break out of its traditional Welsh-speaking heartlands in the north and west, making significant inroads in a constituency that has long been a Labour fortress. The party’s momentum is now undeniable, but the challenge will be maintaining it through to the full Senedd elections in May 2026. Senior Plaid figures, according to BBC, sense that “the tide may finally be going out for Labour in Wales.” They are already allowing themselves to dream of governing Wales outright, or at least as the main party, after next May’s elections.
For Labour, the defeat was not just a setback—it was a humiliation. The party’s candidate, Richard Tunnicliffe, finished a distant third in a seat that Labour’s late Hefin David had won with 46% of the vote in 2021. Labour’s historical roots in Caerphilly run deep, with connections to such towering figures as Keir Hardie, NHS founder Nye Bevan, Michael Foot, and Neil Kinnock. Yet, as BBC analysis points out, “Labour appear to be in deep in the mire.” The result aligns with widespread polling and commentary suggesting Labour is in trouble across Wales, with even some within the party voicing concern. Many Labour figures blame UK leader Sir Keir Starmer for the party’s woes, rather than Welsh First Minister Eluned Morgan, and are calling for a more distinct Welsh Labour identity and a bold policy offer to recapture voters’ imaginations.
There’s growing speculation that Labour’s best hope in the coming Senedd election may not be to govern alone, but rather to limit its losses enough to negotiate a coalition. Some insiders, as noted by BBC, are already floating the idea of a “progressive coalition”—possibly with Plaid, Greens, and Liberal Democrats—to keep Reform UK from gaining a foothold in government. It’s a striking shift from the party’s decades-long dominance and reflects the new political reality in Wales.
Reform UK, for its part, has plenty to cheer despite finishing second. The party’s leap from 2% to 36% of the vote is no small feat, and its campaign in Caerphilly was marked by high energy and the attention-grabbing presence of party leader Nigel Farage. As BBC observed, “The Nigel Farage media show, when it comes to town, is great at capturing attention and so it was here.” While Reform UK didn’t win, its strong showing signals that it’s becoming a force to be reckoned with in Welsh politics, especially as the Senedd prepares to move to a new proportional representation system in 2026. Reform’s own figures remain optimistic about their chances in the coming election, believing that a similar result in May would translate into a significant presence in Cardiff Bay.
One of the most striking features of the by-election was the record turnout—50.43%, according to BBC. This level of engagement suggests that when voters are presented with a real contest and a message of change, they are willing to participate in large numbers. The competitive nature of the race, with Plaid Cymru urging Labour voters to back them to stop Reform UK, proved to be a winning formula. The high turnout and dramatic result have injected a sense of excitement and unpredictability into Welsh politics that has been missing for years. As BBC put it, “The message of change, mixed with some voters being motivated to back Plaid to stop Reform, proved the winning formula for Plaid Cymru this time.”
Looking ahead, the Caerphilly by-election is widely seen as a bellwether for the May 2026 Senedd election. The next six months promise to be among the most exciting and consequential in recent Welsh political history. The established order has been upended, and all parties are now scrambling to adapt to a new landscape where traditional loyalties can no longer be taken for granted. For Plaid Cymru, the challenge is to sustain its momentum and broaden its appeal beyond its core supporters. For Labour, the task is nothing less than existential: can it reinvent itself and regain the trust of Welsh voters, or will it be forced to accept a diminished role in a coalition government? And for Reform UK, the question is whether it can build on its breakthrough and become a permanent fixture in Welsh politics.
One thing is certain: the days of predictable, one-party dominance in Wales are over. The Caerphilly by-election has thrown open the doors to a new era of political competition, and the outcome of next May’s Senedd election is, for the first time in a generation, truly up for grabs.
