Ukip’s founder has dismissed its chances of returning a single MP to Westminster in May, claiming the party is full of far-right sympathisers led by someone who is “obsessed” with immigration and defends racist behaviour.

Dr Alan Sked said the party he established in 1993 was dominated by “the cult of Farage” whose stranglehold over Ukip would sink many potential MPs’ chances of ever taking seats in the House of Commons.

Dr Sked, Professor of International History at LSE, who led Ukip between 1993-97 before falling out with Farage and leaving the party, said: “Given the first past the post system, if they win 15 per cent nationwide Ukip will not get a single seat because you need at least 20 per cent to get in.

In pictures: The rise of Ukip Show all 8 1 /8 In pictures: The rise of Ukip In pictures: The rise of Ukip 1993: Alan Sked forms Ukip History professor Alan Sked had been active in anti-EU politics for a while beore he founded Ukip in 1993. He resigned from the party after the 1997 election, concerned that it was attracting far-right members, and has been critical of Ukip since. Picture: Reuters Reuters In pictures: The rise of Ukip 2005: Kilroy defects Former TV presenter Robert Kilroy-Silk founded Veritas in 2005, after a failed bid to become leader, and took many of Ukip's elected members with him. But the party slowly lost its popularity and didn't put forward any candidates in the last election. Picture: REUTERS/Kieran Doherty REUTERS KD/RUS In pictures: The rise of Ukip 2010: Farage becomes leader, again Farage had led Ukip from 2006 until 2009, when he stood down to fight against the Speaker, John Bercow, for his Buckingham seat. He failed to win the election and returned to lead the party in November 2010. Picture: REUTERS/Kieran Doherty REUTERS/Kieran Doherty In pictures: The rise of Ukip 2010: Ukip fights for election Nigel Farage was injured in a plane crash on polling day in the 2010 general election, but his party increased its success in the votes. It fielded 572 candidates and took 3.1% of the vote, though failed to win any seats. REUTERS/Darren Staples REUTERS/Darren Staples In pictures: The rise of Ukip 2013: Eastleigh gains Ukip's candidate Diane James got the highest ever number of votes for any candidate from the party, but was beaten by the Liberal Democrats. The surge in support gave Ukip confidence ahead of local and European elections later in the year. Picture: Reuters In pictures: The rise of Ukip 2013: Bloom kicked out Godfrey Bloom, who served as an Ukip MEP from 2004 to 2014, had the whip withdrawn in 2013 after sexist comments and an attack on a journalist. He sat as an independent MEP until 2014, when he ended his term in office. Picture: REUTERS/Luke MacGregor In pictures: The rise of Ukip 2014: European election success Ukip got a higher proportion of the vote than any other party in 2014's European elections, adding 11 new MEPs and taking its total to 24. REUTERS/Luke MacGregor In pictures: The rise of Ukip 2014: Carswell defects Douglas Carswell defected from Ukip at the end of August, and was followed by Mark Reckless at the end of September, who resigned from the Tories amid rumours of many more defections to come. Picture: REUTERS/Toby Melville

“My great whinge about Ukip is not just their racism and their lurch to the far-right but to lots of people in the country they are simply toxic and wouldn’t touch them with a barge pole. If Farage dominates and monopolises the UK campaign then he will sink it, because there are lots of people who might be anti-EU but wouldn’t vote Ukip.

“In 2010, while we’re in the midst of an enormous economic crisis, Ukip’s manifesto could be summed up as ‘ban the burqa’. Then, of course, Farage said the whole manifesto was ‘sheer drivel’ but he’s been speaking drivel ever since.”

Dr Sked said Ukip under Mr Farage had transformed itself into something unrecognisable compared to when he founded it as “a mainstream, liberal party to defend British parliamentary democracy from Europe and the EU”.

He said: “We never talked about immigration. We had policies about defence, the economy, the welfare state, all sorts of things, but there wasn’t one on immigration because it was of no interest to me and the party when it was founded. Once Farage took over the party became more and more right wing.

“Now party members are making all sorts of embarrassing statements about blacks, Chinese, Islam or something else.”

Dr Sked cited Mr Farage’s defence of the use of the word ‘Chinky’, which former Ukip parliamentary candidate Kerry Smith used to describe Chinese people, as an example of how far Mr Farage is prepared to go to defence racist comments in public.

Dr Sked pointed to one notorious meeting Mr Farage had with far right activists as reason why he wanted to leave the party he founded. Mark Deavin, a former PhD student of Dr Sked’s and BNP activist, managed to infiltrate Ukip in the late 1990s and was photographed after a lunch meeting with Mr Farage alongside the twice-jailed BNP activist Tony ‘the bomber’ Lecomber. Dr Sked admitted bringing Deavin into Ukip but said he had “no idea” he was research director of the BNP.

Dr Sked said: “When I found out I expelled him from the party and denounced him on television. But Farage met up with him and the BNP took a photograph of them outside the place where they had lunch.”

A Ukip source told The Independent it was “pretty cheap” for Dr Sked to bring up the meeting again, claiming it was the LSE lecturer who introduced Mr Farage to Deavin and that Lecomber ‘photobombed’ the meeting in a BNP set up.

Dr Sked said he now regarded Mr Farage as “a barroom bore with little education” who has created a stranglehold over Ukip.

“The party is a cult controlled directly by Farage. Anyone who criticises him gets thrown out or bumped off the National Executive Committee because he can’t take criticism.”

The only common ground between the pair now is their shared admiration for the former Tory minister Enoch Powell. Letters from Mr Farage and Dr Sked to Powell, written in the 1990s, were published last month asking him to join their cause.

Dr Sked said the invitations were because of Powell’s well-known Euroscepticism, rather than his controversial stance on immigration following his infamous ‘rivers of blood’ speech.

“I don’t think he was a racist. His Wolverhampton constituency had so much immigration that he couldn’t not talk about it because he was under such local pressure to do so. I met him a few times and was at his house a few times and he never mentioned anything that was slightly or remotely racist.

“Powell was also a great anti-European and was the one that led the no campaign at the 1975 referendum. Powell was never obsessed by immigration but Farage is.”