Plaid Cymru win Caerphilly by-election as Labour lose historic stronghold

Plaid Cymru has won the Caerphilly Senedd by-election, taking the seat from Labour in what Plaid described as a major victory ahead of next year’s Welsh Parliament elections.

Lindsay Whittle, the Plaid Cymru candidate and former Assembly Member, defeated Reform UK’s Llyr Powell and Labour’s Richard Tunnicliffe to secure the seat. The result ends Labour’s long-standing hold on the constituency and comes six months before the 2026 Senedd election.

The result marks a significant shift in the political landscape of South Wales, with Plaid Cymru gaining ground in an area traditionally dominated by Labour. Reform UK also made notable inroads, finishing ahead of Labour in the contest.

Reactions from Party Leaders

Plaid Cymru leader Rhun ap Iorwerth said the result showed growing support for his party’s “pro-Wales vision” and a desire for “positive change”.

“Tonight, the people of Caerphilly have spoken loud and clear. They’ve chosen hope over division, and progress over the tired status quo,” he said.

“Lindsay Whittle is a tireless local champion who knows every community in this constituency inside out and will deliver real change for the people of Caerphilly.”

Mr ap Iorwerth added that the outcome demonstrated Plaid Cymru’s growing position as a key challenger to Reform UK, claiming it showed that Wales was “ready for new leadership”.

Welsh Labour Responds to Defeat

First Minister of Wales, Eluned Morgan, acknowledged the challenges faced by her party in the Caerphilly by-election and congratulated Plaid Cymru’s Lindsay Whittle on his victory.

“This was a by-election in the toughest of circumstances, and in the midst of difficult headwinds nationally,” she said. “I want to thank our candidate, Richard Tunnicliffe — a good man who stood because of his desire to serve his community.

I congratulate Lindsay Whittle on his victory tonight. He returns to the Senedd, continuing his many decades of elected service to people in Caerphilly.”

The First Minister added that Welsh Labour had “heard the frustration on doorsteps” and accepted responsibility for the result.

“We are listening, we are learning the lessons, and we will come back stronger,” she said.

Whittle Pledges Local Focus

In his acceptance speech, Mr Whittle thanked voters for their support and said he would focus on practical issues affecting residents.

“It will be my honour to serve as your new member of the Senedd,” he said. “I’m ready to get to work straight away by making sure our local schools are properly supported, our libraries stay open, our GPs see people when they need to, and that everyone in Caerphilly gets the same chance to do well.”

Mr Whittle added that the result showed what could be achieved “when people come together to back practical solutions and protect what matters most”.

Implications Ahead of 2026

The Caerphilly result is expected to intensify competition between Plaid Cymru, Labour, and Reform UK ahead of the 2026 Senedd election. Analysts say the result reflects wider shifts in voter sentiment in parts of South Wales once considered Labour strongholds.