Plaid Cymru has won the Caerphilly by-election for the Welsh Parliament, defeating Reform UK as Labour finished in third. The party secured a majority of 3,848 votes and a swing of almost 27 percentage points from Labour, achieved on a turnout above 50%. The result boosts Plaid ahead of a Welsh Government budget vote and represents a setback for Labour, which had held the seat since the Senedd’s inception in 1999.

Lindsay Whittle won 15,961 votes, just over 47% of the total, with a swing of about 19 percentage points since 2021. Reform’s Llyr Powell finished second with 12,113 votes, a marked rise from four years ago when the party had only 495. Labour’s candidate, Richard Tunnicliffe, trailed on 3,713, down from 13,289 in 2021. The Conservatives recorded 690 votes, while the Greens and Liberal Democrats had 516 and 497 respectively.

Plaid Cymru leader Rhun ap Iorwerth said Caerphilly had spoken clearly, backing Plaid’s pro‑Wales vision and a move away from the status quo. Whittle said he had served the community all his life and that the result shows what is possible when people back practical solutions, adding that the party must now deliver for Caerphilly and for Wales. Powell predicted Reform would form a government in 2026 and urged more people to vote, while Labour’s First Minister Eluned Morgan acknowledged the by-election occurred under difficult national conditions, accepted responsibility, and pledged that Labour would come back stronger.