Plaid Cymru, the Welsh nationalist party long regarded as an underdog in South Wales, has achieved a stunning and historic victory in the Caerphilly by-election, upending over a century of Labour dominance and sending shockwaves through the political establishment. The contest, held on October 23, 2025, with results announced in the early hours of October 24, saw Plaid candidate Lindsay Whittle secure 15,961 votes—47% of the total—leaving Reform UK, the far-right populist party, in second place with 12,113 votes (36%), and Welsh Labour trailing in a distant third at just 3,713 votes, or 11%. The turnout surpassed 50%, a notable figure for a by-election in the Welsh Valleys.
The by-election was triggered by the death of Hefin David, the sitting Labour Member of the Senedd, earlier this year. The contest quickly became a focal point for national political tensions, as Reform UK, led by the ever-controversial Nigel Farage, poured significant resources into the campaign, hoping to claim its first seat in the devolved Welsh parliament. Labour, meanwhile, faced mounting criticism over its perceived drift toward the political center and its handling of issues such as austerity, migration, and the cost-of-living crisis.
As the votes were counted, the atmosphere in Caerphilly was electric. Plaid Cymru’s leader, Rhun ap Iorwerth, was the only leader of a major party to attend the count, a move that underscored Plaid’s growing confidence and ambition. When the final bundles were tallied, the result was clear: Labour had lost the seat for the first time since the Senedd’s creation in 1999, and for the first time in Westminster elections since 1918. Reform UK, while falling short of victory, had dramatically increased its vote share from less than 500 four years ago to over 12,000—an achievement that placed them well ahead of Labour but not quite enough to topple Plaid’s surge.
In his acceptance speech, Lindsay Whittle struck a tone of both humility and excitement. "Ladies and gentlemen, I'm not used to speaking first. Whilst we are perhaps euphoric in some parties tonight, I respectfully ask you to remember why we are here—under sad circumstances. We pay tribute to Hefin David, his family and friends, and I extend my sympathies. He will be a hard act to follow. I will walk the same path he did, and I can pay no finer tribute to an excellent man," Whittle said, as reported by Herald Wales. He continued, "This is better than scoring the winning try against New Zealand in the final of the Rugby World Cup. I promise you, Caerphilly—I will serve you to the best of my ability."
The significance of the result was not lost on Plaid Cymru’s leadership. Rhun ap Iorwerth, celebrating the breakthrough, declared, "Tonight, the people of Caerphilly have spoken loud and clear; they've chosen hope over division, progress over the tired status quo, and backed Plaid Cymru's positive, pro-Wales vision." He added, "This result shows that Plaid is no longer just an alternative, we are now the real choice for Wales, the only party able to stop billionaire-backed Reform and offering a better future that works for everyone." (openDemocracy)
For Labour, the defeat was a bitter pill. The party had held Caerphilly for generations, both in Westminster and the Senedd, making this loss a symbolic blow to its standing in the heartlands. Welsh First Minister Eluned Morgan acknowledged the gravity of the situation, stating, "This was a by-election in the toughest of circumstances, and in the midst of difficult headwinds nationally. Welsh Labour has heard the frustration on doorsteps in Caerphilly that the need to feel change in people's lives has not been quick enough. We take our share of the responsibility for this result. We are listening, we are learning the lessons, and we will come back stronger." (openDemocracy)
Reform UK, for its part, tried to put a brave face on the outcome. Candidate Llyr Powell predicted, "I think, next May, we're going to form a Reform government. Moving forward, you can see Labour in decline, and there's one party that's surging here, and you can see from tonight's result that's Reform UK. I'm very excited for what we're building here in Wales." (openDemocracy) Despite the defeat, Reform’s leap in support—from fewer than 500 votes to over 12,000—signals a volatile and unpredictable political landscape ahead of the full Senedd elections in May 2026.
The Peace and Justice Project, a progressive group, weighed in on the broader implications, writing on social media, "This Senedd by-election result shows that people are sick of the Westminster establishment and its persistent scapegoating of marginalized communities instead of effectively dealing with the issues we all face." They argued that the result demonstrated how "progressive alternatives can still stop the far right in British politics," pointing to Plaid’s win as evidence that voters are open to new, hopeful visions beyond the traditional parties.
Plaid Cymru itself is a center-left, social democratic party that advocates for Welsh independence from the United Kingdom, though not at any cost or on any immediate timetable. Rhun ap Iorwerth has recently proposed a "standing commission" to consider independence if Plaid wins both the 2026 and 2030 Senedd elections. The party’s platform, emphasizing practical solutions and a positive, pro-Wales agenda, appears to have resonated with voters disillusioned by both Labour’s perceived inertia and Reform UK’s divisive rhetoric.
The by-election’s outcome has also energized other progressive forces in the UK. The Green Party, newly led by Zack Polanski, has announced a doubling of its membership to 140,000, while independent MPs Jeremy Corbyn and Zarah Sultana’s new left party has reportedly drawn over 600,000 expressions of support. These groups, like Plaid, have positioned themselves as bulwarks against the rise of far-right populism and as critics of Labour’s shift to the center under Prime Minister Keir Starmer.
Looking ahead, the battle lines for the 2026 Senedd elections are already being drawn. Reform UK, buoyed by its strong showing, will likely continue to pitch itself as the main challenger to the status quo, while Plaid Cymru will seek to build on its momentum and position itself as the party of hope and practical change. Labour, chastened but unbowed, must now reckon with the depth of voter dissatisfaction and chart a path back to relevance in its former heartlands.
For now, though, the people of Caerphilly have spoken, and their message is clear: the old political certainties are crumbling, and a new era of Welsh politics may just be dawning.
