Carswell also insisted he was happy for UKIP leader Nigel Farage and deputy leader Paul Nuttall to take the lead ahead of the election. He said he was focused on keeping his seat in Clacton, Essex, in May's general election – even though he won October's by-election with a thumping 12,404 majority.

"I'm not one of UKIP's major players," he said. "I will never hold ministerial office, that's just my personal choice. I'm not playing that game, I'm not playing that level. UKIP has some absolutely first-class people in it who I think will go all the way but my job is to help support that, help with the key seats campaign, help in supportive role with policy."

He said the party was turning itself around after dealing with a string of "outrageous" comments from parliamentary candidates and councillors last year. They include would-be MP Kerry Smith who quit after describing gay people as "fucking disgusting old poofters" and calling a woman with a Chinese name a "chinky". Meanwhile, councillor Rozanne Duncan was expelled from UKIP for allegedly saying she had a problem with "negroes" because there was "something about their faces".

Carswell said: "By definition any organisation that starts outside the political mainstream is going to attract one or two people in its ranks whose views are simply outside the mainstream, and UKIP's had one or two people with views that are offensive.

"The key thing is what UKIP's done about it. Five years ago, maybe two years ago, UKIP may have taken the view that, you know, let's all move along. Now, look at what happened with one of its recent candidates that said things that are outrageous. The point is not that UKIP had a candidate that said outrageous things, it's that once that came to light and people knew that was the truth, that person was no longer a UKIP candidate and never will be.

"Before Christmas, UKIP came in for some stick and deservedly so – because actually the significance of that Christmas period is that it was a watershed period for UKIP. Since then I think UKIP has really upped its game. We've got A-grade candidates, a very diverse mix of people, but they're all people who are respectable and decent and who recognise that in a democracy every individual is fundamentally equal."