This is Nigel Farage’s chance to deliver a blow to Sir Keir Starmer which will make the loss of Gorton and Denton seem like an electoral hiccup. Reform UK is on course to be one of the top two parties in the Welsh parliament, the Senedd. Labour has been the biggest party since Tony Blair ignited the devolution era in 1999 – and it has topped the poll in every Westminster election in Wales for more than a century.

There will be relief amid the agony if Labour musters a third place finish in the May elections. If Reform can bring Labour rule to an end in the Senedd the prospect of it doing the same in Westminster will be even more credible.

Reform’s manifesto, launched today, sets out its vision for change in Wales, a nation where wages lag significantly behind the English average, where children perform worse than their peers in the other UK nations in reading, science and maths, and where families swap horror stories about their NHS experiences.

Wales backed Brexit in the 2016 referendum but the Conservatives have struggled to thrive in Senedd elections. Reform lacks the stigma which stopped many people in former industrial communities voting Tory and it has proved adept at tapping into grievances.

Pledges such as scrapping the 20mph speed limit and building a M4 relief road show a Reform government would not be beholden to environmental concerns which have shaped Welsh policymaking for so long. They also want to ban new onshore wind and solar farms, and knock a penny off every income tax band.

Wales’ electoral system means it is hard for any one party to win a majority and few people will be surprised if a Plaid Cymru-led government emerges. It has propped up Labour in the past and it is not hard to imagine a role reversal that ensures the soft Left continues to run the nation.

But the spectacle of Reform being the main opposition, having demolished the Tories and scored victories through Labour’s traditional heartlands would still send shockwaves throughout the UK. It would deepen fears in Labour ranks that Mr Farage can win over even greater swathes of the Red Wall than Boris Johnson did in 2019.

And if Reform’s Welsh leader somehow becomes the first non-Labour First Minister then the party can claim Wales is the beachhead in a populist revolution that will shake-up the whole country.

Labour has never reclaimed control of the Scottish government after its 2007 election defeat. If it loses hold of Wales, too, and suffers a local government disaster in England, serious questions will be asked about the party’s future. Wales was once a bastion of Liberal Democrat support but the party won a single constituency in 2024. Labour will be desperate to avoid a similar vanishing act.

If Sir Keir sees a collapse of support in the political homeland of Keir Hardie, Aneurin Bevan and Neil Kinnock then – as Mr Farage has predicted – the Starmer era could come crashing to an end.