Labour has been crushed in the Caerphilly by-election, losing a seat it had held for over a century in a devastating blow that saw the party slump to third place behind Plaid Cymru and Reform UK.
Lindsay Whittle of the Welsh nationalist party stormed to victory with 15,961 votes, comfortably beating Reform UK’s 12,113 in second place. Labour collapsed to just 3,713 votes, representing a catastrophic 34.9 per cent decline compared to the 2021 Senedd election.
The result marks the end of Labour’s unbroken dominance in the Valleys town, which has returned Labour candidates in every Westminster election since the seat was created in 1918. At the Welsh Parliament level, Labour had maintained control since devolution in 1999, making Thursday’s defeat a seismic shift in Welsh politics under Sir Keir Starmer’s leadership.
Turnout reached 50.43 per cent, with 33,736 ballot papers counted, a significant increase from the 44.31 per cent recorded in 2021. The higher participation suggests voters were motivated to deliver a verdict on the Government’s performance.
The by-election was triggered following the death of Labour MS Hefin David. Victorious candidate Whittle paid tribute to his predecessor as he celebrated his landmark win, saying David would be a hard act to follow. He promised never to fill his shoes but vowed to walk the same path, calling it the finest tribute he could pay to an excellent man.
Whittle declared the victory marked an exciting time for Welsh politics as he laid down a challenge to Westminster. He proclaimed Wales stands at the dawn of a new beginning and looked forward to playing his part in creating a new Wales. The jubilant winner compared his triumph to scoring the winning try for Wales against New Zealand in the Rugby World Cup.
Plaid Cymru leader Rhun ap Iorwerth seized on the result to attack what he described as tired Labour leadership. He declared that the people of Caerphilly had spoken loud and clear, choosing hope over division and progress over the tired status quo whilst backing Plaid Cymru’s positive, pro-Wales vision.
Ap Iorwerth praised Whittle as a tireless local champion who knows every community in the constituency inside out and will deliver real change for Caerphilly residents. The endorsement positions the new MS as a grassroots figure with deep local connections rather than a parachuted candidate.
Labour sources attempted damage limitation even before the devastating result became official. Speaking to GB News moments before the count, Cardiff Central MP Alex Barros-Curtis insisted his party still had plenty of time to turn things around, suggesting confidence that electoral fortunes could improve before the next scheduled elections.
One Labour insider, speaking earlier in the week, characterised the expected defeat as a rejection of Starmerism rather than Welsh First Minister Eluned Morgan. The source claimed Baroness Morgan, who has served as First Minister since August 2024, had proven relatively popular on the doorsteps during campaigning.
The attempt to separate Welsh Labour’s performance from the wider UK party’s troubles reflects growing tensions between Cardiff Bay and Westminster as the Starmer Government’s approval ratings continue to slide across Britain.
Reform UK’s Zia Yusuf struck a conciliatory tone in defeat whilst celebrating his party’s dramatic surge in support. He congratulated Whittle before highlighting that Reform winning 36 per cent, up from just 1.7 per cent in 2021, represented a remarkable achievement.
Yusuf declared the result a historic realignment in Welsh and British politics, positioning next May’s Senedd elections as a battle between Reform and Plaid Cymru. He expressed astonishment that Labour had fallen to just 11 per cent whilst the Conservatives managed only two per cent, describing the collapse of the uniparty vote from 63 per cent four years ago to just 13 per cent as extraordinary.
The Reform chairman hinted that candidate Powell, whom he described as a hard worker, may yet taste success at the Senedd election as he vowed the Reform resolve is stronger than ever. The statement suggests the party views Wales as fertile territory for further gains.
The Conservative Party’s humiliation, securing just two per cent of the vote, underscores the total collapse of traditional two-party politics in this Welsh heartland. The Tories‘ near-obliteration suggests voters view them as irrelevant to Welsh political discourse.
Political analysts will scrutinise whether Caerphilly represents a localised protest vote or signals broader trends that could reshape the May 2026 Senedd elections. Labour faces difficult questions about whether its Westminster agenda resonates with Welsh voters or whether devolution has created diverging political cultures.
The result also raises questions about Welsh independence sentiment and whether Plaid Cymru’s nationalism finds increasing traction as disillusionment with London-based parties grows. The party’s ability to attract former Labour voters in traditional heartlands could prove transformative.
For Starmer’s Government, the Caerphilly catastrophe adds to mounting electoral setbacks that have plagued Labour since taking power. By-election defeats and council losses have chipped away at the commanding authority the party enjoyed following its landslide general election victory.
Labour strategists must now confront uncomfortable truths about their appeal in working-class communities that once formed the bedrock of their support. The party’s shift towards metropolitan priorities appears to have alienated voters in post-industrial regions who feel ignored and taken for granted.
The rise of Reform UK across Wales mirrors patterns seen in England, where Nigel Farage’s party has hoovered up disaffected Conservative and Labour voters who feel mainstream parties have failed them on immigration, economy and national identity.
Plaid Cymru’s victory, however, suggests Welsh voters possess distinct concerns beyond those animating English politics. Questions of Welsh autonomy, language rights, economic development and relationships with Westminster create a unique political landscape that cannot be simply mapped onto broader UK trends.
As parties digest the Caerphilly shock, attention will turn to whether this represents a one-off upset or the beginning of fundamental political realignment in Wales. Labour can ill afford further erosion of its Celtic strongholds if it hopes to maintain power both in Cardiff Bay and Westminster.
The coming months will test whether Labour can arrest its decline or whether Welsh politics has entered a new era where the party’s century of dominance becomes a fading memory.
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Image Credit:
Prime Minister Sir Keir Starmer hosts the Council of the Nations & Regions — photo by Simon Dawson / No 10 Downing Street, licensed under CC BY 2.0 via Wikimedia Commons.
