Ian Gribbin, who is aiming to oust the Conservatives in Bexhill and Battle in East Sussex, also reportedly wrote online that women were the “sponging gender” and should be “deprived of health care”.

The BBC reported that in posts allegedly made in 2022 on the UnHerd magazine website, Mr Gribbin said Sir Winston Churchill, the wartime prime minister, was “abysmal” and praised Vladimir Putin.

Mr Gribbin declined to comment when approached by the BBC but a Reform spokesman said the alleged comments were not “endorsements” but “written with an eye to inconvenient perspectives and truths”, while his remarks about women were “tongue in cheek”.

In July 2022, Mr Gribbin reportedly posted on the UnHerd website: “Britain would be in a far better state today had we taken Hitler up on his offer of neutrality … but oh no Britain’s warped mindset values weird notions of international morality rather than looking after its own people.”

The same month he reportedly wrote: “In Britain specifically we need to exorcise the cult of Churchill and recognise that in both policy and military strategy, he was abysmal.”

Reform UK is hoping to take votes from the Conservatives and has seen a boost in the polls since Nigel Farage became leader last week.

The party is standing more than 600 candidates across the country but one of its contenders has already withdrawn from the race to back the Conservatives instead. The candidate axed to make way for Mr Farage is now standing against him as an independent.

The latest revelations will raise fresh questions about the suitability of some of Reform’s candidates and the party’s vetting process.

The BBC reported that Mr Gribbin is also said to have allegedly criticised women, writing on UnHerd’s message board: “Do you think you could actually work and pay for it all too like good citizens?

“Men pay 80 per cent of tax – women spend 80 per cent of tax revenue. On aggregate, as a group, you only take from society.

“Less complaining please from the ‘sponging gender’.”

He added that women were “subsidised by men to merely breathe” and in January 2022 he also posted: “Men pay 80% of tax. Women take out 80% of expenditures.

“Square that inequality first by depriving women of healthcare until their life expectancies are the same as men, fair’s fair.”

Two months earlier, in December 2021, he reportedly wrote female soldiers “almost made me wretch (sic)” and were a “total liability”. 

In the run-up to the invasion of Ukraine, he praised Putin, writing in January 2022 that he had “shown a maturity of which we can only dream of”.

He “understands the bonds that create more stable societies; the hypocrisy of the West is preposterous as we stare in the face daily the enormous economic equalities created by our deluded neo-liberal ideas”, he wrote.

In February, Mr Gribbin also allegedly wrote “if only the West had politicians of his class”.

Bexhill and Battle has been held by Huw Merriman, a transport minister, since 2015 but he is standing down at the election. At the last election, Mr Merriman secured a majority of more than 26,000.

A Reform UK spokesman said: “Through offence archaeology, the BBC has found that Mr Gribbin has made a series of comments about a number of subjects.

“They were written with an eye to inconvenient perspectives and truths. That doesn’t make them endorsements, just arguing points in long-distance debates.

“His historical perspective of what the UK could have done in the 30s was shared by the vast majority of the British establishment including the BBC of its day, and is probably true.

“Again no endorsement, just pointing out conveniently forgotten truths.

“As for the feminism point, his tongue is so firmly in his cheek one should be able to spot it from 100 yards.”