Plaid Cymru has won the Caerphilly by-election with 15,961 votes, defeating Reform UK's 12,113 votes and Labour's 3,713 votes, marking the first time Labour lost this Welsh heartland seat in over a century with a swing of almost 27% from Labour to Plaid.
UK: Plaid Cymru Wins Caerphilly By-Election, Ends Labour's Century Rule