The people of Caerphilly made history yesterday. In a by‑election triggered by the death of Labour MS Hefin David in August, voters turned out in unexpectedly high numbers to deliver a decisive victory for Plaid Cymru. The result not only ended more than a century of Labour dominance in the constituency but also signalled a profound shift in Welsh politics ahead of next year’s Senedd elections.

The Last of First Past the Post

The by‑election was unusual from the outset. Whoever won would serve only until 7 May 2026, when the next Senedd elections are scheduled. That contest will be the first held under a radically reformed, and fairly confusing electoral system.

From 2026, the Senedd will expand from 60 to 96 Members. Wales will be divided into 16 multi‑member constituencies, each electing six MSs. Voters will cast a single ballot for a party or independent candidate, with seats allocated by a closed proportional list system, a form of proportional representation designed to reduce wasted votes and better reflect the national share of support.

That made Caerphilly the last Senedd election to be decided by the blunt instrument of first past the post. It also meant the result was watched closely as a bellwether for how Wales might vote under the new system.

A Town Left Behind

Caerphilly is no stranger to political symbolism. Once a Labour fortress, the constituency has long embodied the struggles of post‑industrial Wales. Yet despite the rhetoric of Reform UK, immigration was never likely to be the decisive issue here. According to the 2021 Census, just 2.9% of Caerphilly’s population is foreign‑born – far below the UK average of 14%.

The real story is one of economic neglect. For decades, residents have complained that Westminster governments of all stripes have funnelled investment into England while branding projects as “England and Wales.” The sense of being short‑changed has only deepened as debates rage over whether Wales should, like Scotland, control its share of the Crown Estate. Scotland gained that power in 2016, reaping more than £100 million annually from offshore wind and other assets. In Wales, however, revenues still flow to the UK Treasury and the monarchy.

A Two Horse Race

From the outset, this was a two‑horse race. Labour, once unassailable, has been battered by association with its unpopular UK leadership and by scandals closer to home. Vaughan Gething’s short tenure as First Minister in 2024 was marred by controversy over a £200,000 campaign donation and cabinet resignations that left Welsh Labour in turmoil.

Plaid Cymru, by contrast, ran a campaign rooted in community. Activists from across Wales poured into Caerphilly, knocking on doors and emphasising bread‑and‑butter issues: underfunded services, the need for devolved control of resources, and the promise of a government that puts Wales first.

Reform UK, meanwhile, imported its star names from England. Nigel Farage, Richard Tice and Zia Yusef all appeared on the campaign trail, hammering their familiar “stop the boats” message. But in a constituency with negligible immigration, the rhetoric rang hollow. As Lindsay Whittle put it in his conference address, people were “sick to death of fancy men from London coming here in their fancy suits”  and the campaign’s reception seemed to prove him right.

Whittle brought to the contest the weight of more than half a century in public life. A lifelong Caerphilly resident and veteran councillor, Whittle’s campaign leaned heavily on his deep local roots and decades of service, presenting him as the embodiment of continuity and commitment to the community.

By contrast, Reform’s Llŷr Powell cut a far less established figure. A former Conservative candidate, Powell’s more recent political experience came as an assistant to Nathan Gill – the disgraced former leader of Welsh Reform who has since admitted in court to accepting Russian bribes. The juxtaposition could hardly have been starker: Whittle, the seasoned local stalwart, against Powell, whose ties to a tainted political past cast a long shadow over his candidacy.

Polls, Turnout and the Result

For weeks, polls suggested Reform was narrowly ahead, with Labour languishing in third. Some surveys gave Reform a lead of two to five points. Yet the old saying, never trust the poll, proved true once again.

Turnout reached 50.43%, the highest ever for a Senedd by‑election. That figure is remarkable in a chamber where general election turnouts often hover closer to 45%.

The final tally was emphatic:

•           Plaid Cymru (Lindsay Whittle): 15,961 votes – 47.4%

•           Reform UK (Llŷr Powell): 12,113 votes – 36.0%

•           Labour (Richard Tunnicliffe): 3,713 votes – 11.0%

•           Conservatives: 690 votes — 2.0%

Plaid not only beat Reform but secured more votes than Reform and Labour combined. The scale of Labour’s collapse – a swing of nearly 35% away from the party was as striking as Reform’s failure to convert hype into victory.

Why Plaid Won

Two dynamics proved decisive. First, tactical voting. Many Labour supporters, unwilling to see Reform claim its first directly elected Senedd seat, lent their votes to Plaid. Second, the youth vote. Plaid Ifanc, the party’s youth wing, mounted an intensive ground campaign, canvassing peers and stressing the stakes of the contest.

The result was a surge of younger voters who turned out in numbers rarely seen in Welsh by‑elections. Their support helped Plaid transform what had been forecast as a knife‑edge contest into a comfortable majority of 3,848 votes.

Lessons Beyond Wales

The implications stretch far beyond Caerphilly. For Labour, the loss of a seat it had held since the Welsh Assembly’s creation in 1999 is a humiliation. For Reform, the defeat punctures the narrative of unstoppable momentum. And for Plaid, the victory cements its claim to be the only party capable of challenging both Westminster unionism and Farage‑style populism in Wales.

But the lessons resonate further south too. In Cornwall, where Mebyon Kernow has long argued that Westminster neglect mirrors that of Wales, the Caerphilly result offers a template. Mobilising young voters, asserting cultural pride, and framing progressive nationalism as the antidote to divisive populism may be the only way to keep Reform at bay.

As in Wales, so in Cornwall: only parties rooted in their communities, speaking their languages and defending their resources, can hope to resist the tide of English‑led populism. In Scotland, that means the SNP. In Wales, Plaid Cymru. And in Cornwall, Mebyon Kernow.

More than a local contest

The Caerphilly by‑election was more than a local contest. It was a referendum on the future of Welsh politics, fought in the shadow of constitutional change and economic neglect. The people of Caerphilly chose hope over division, local representation over imported rhetoric, and a vision of Wales that governs itself.

When the Senedd elections arrive in May 2026, the new proportional system will reshape the political landscape. But if Caerphilly is any guide, the momentum is with those who speak for their communities, not at them.

Image Via: Instagram – Plaid Cymru.