REVEALED: The ex-Labour voters switching to Reform UK who could propel Nigel Farage to No10

A survey conducted by Survation last week placed support for Reform UK at 42 per cent, up 40 points since the 2021 Welsh Parliament Election.

Meanwhile, Plaid Cymru received a 10 per cent boost to take them to 38 per cent.

Labour's support has all but collapsed since Sir Keir Starmer came to power last July, falling to just 12 per cent in Survation's survey.

Speaking to GB News, Survation's chief executive Damian Lyons Lowe said: "The main story is that Labour's 2021 base has collapsed.

"There's just a third of their base remaining. A third have gone to Plaid and a quarter to Reform."

The polling guru pointed out that Reform is performing particularly strongly with Caerphilly's Brexit-backing residents.

Meanwhile, Plaid Cymru, which has always had a strong base in the town, is picking up additional support from younger voters.

But campaigners on the ground do not anticipate Labour's support falling to as low as 12 per cent. "I think Labour's vote is being understated," a rival campaign source told GB News.

"This place has always been Labour. There's been a massive shift, but some will stay loyal."

Welsh Labour has conceded that it will be a tough task to cling onto Caerphilly, despite first snatching the seat in 1918. "We’re not shying away from the fact this has been a difficult campaign at a difficult time for governments both here and in London," a Welsh Labour source said.

"We’ve spoken to tens of thousands of voters since the start of this by-election and we’re hearing those frustrations on the doorsteps.

"But there’s also real concern about letting Reform in and bringing their divisive brand of politics with them."

However, Survation's findings could boost Reform UK's efforts to win other large swathes of formerly Labour-voting, Brexit-backing constituencies.

Runcorn & Helsby perhaps gave Reform UK a taste of the potential, but Caerphilly could bring dozens of seats into play that refused to budge when Boris Johnson toppled the Red Wall.

When asked why Wales was appearing to give Reform UK a chance, Mr Lyons Lowe suggested that Mr Farage had built a foundation on the other side of the River Severn.

He told GB News: "Twenty-nine out of 40 Welsh constituencies voted leave in 2016.

"Then, in the 2021 Senedd Election, 30 per cent of voters voted for either right-leaning or anti-Assembly parties.

"And the Brexit Party topped the polls in Wales in the 2019 EU Parliament Election with 29 per cent. What we’re seeing here is a consolidation of an existing trend, rather than Wales changing as a nation.”

Survation's survey also found that Reform UK snatched 70 per cent of 2021 Tory voters, taking Conservative support in Caerphilly down to just four per cent.

The Tory Party, which has never won a majority of seats in Wales, is now facing a catastrophic scenario where it falls from second to fourth place.

While the Senedd is expanding from 60 to 96 members, many campaigners now believe the Tories could collapse to just three MSs.

"They [MSs] haven’t gone to Caerphilly," one Tory source told GB News. "They’ve been too busy trying to keep my own seat."