Ukip leader says all policies are under review and he will not commit to new ones until after European elections

Nigel Farage has disowned his party's entire 2010 election manifesto after he was asked whether the UK Independence party still wanted to introduce a dress code for taxi drivers, regularly deploy armed forces on the street and repaint trains in traditional colours.

The Ukip leader said all the party's policies were under review and he would not commit to new ones until after the European elections in May.

Speaking on BBC2's Daily Politics, Farage argued he was not in charge of the party in 2010 as he was just a candidate – despite having previously led the group between 2006 and 2009. "I don't defend the 2010 manifesto. I didn't put it together," he said.

Farage addressed the issue again during a lecture at the London School of Economics, emphasising the party "got it wrong" when it came to publishing policies at the last election.

He also gave his predictions for the European elections, saying David Cameron and Nick Clegg could face leadership challenges if they do very badly.

In a frank admission about his own political career, Farage also said it would be "curtains" for his time as Ukip leader if the party comes third in the contest, although he is hopeful of coming first.

Asked about possible alliances in Europe, the MEP hinted he could be willing to team up with the populist Italian group of Beppe Grillo.

However, he insisted that he would not go anywhere near "ghastly" far-right parties that he believes are threatening the eurosceptic cause across the continent.

His attempt to distance Ukip from its manifesto of four years ago may put Farage under more scrutiny about what the party stands for in the run-up to the May elections.

In a series of 2010 documents, Ukip proposed detailed plans such as capping the number of foreign players in football teams, bringing back "proper dress" to the theatre, scrapping paid maternity leave, allowing corporal punishment in schools and holding referendums on new places of worship such as mosques.

Other ideas included making the Circle line tube on London underground circular again, investigating discrimination against white people at the BBC, and teaching schoolchildren more about the role of Arabs and African states in slavery.

Earlier, Farage floundered on live television as he was asked about the party's proposal to scrap Trident, saying he was not sure where the interviewer had got this suggestion from. When told it was on the Ukip website, he said: "When it comes to websites, I'm not the expert."

Challenged over a compulsory dress code for taxi drivers, he said: "Do we? News to me … look, under the last leadership and in the 2010 election we managed to present a manifesto that was 486 pages long. So you can quote me all sorts of bits of it that I will not know. That's why I've said none of it stands today and we will launch it all after the European elections."

Asking about a policy to repaint trains in traditional colours, Farage said: "I've never read that. I've no idea what you're talking about."

However, he said it was not "obvious nonsense" that he could cut £90bn of taxes and increase spending by £30bn, even though that would be ambitious.

Asked for a concrete example of a policy that would be in the 2015 manifesto, the Ukip leader said he would bring back grammar schools as well as leaving the EU.

Farage was also attacked on the programme for his comments about women in the City being "worth less" to employers after they have had children. Louise Cooper, a financial analyst, said he should be ashamed of setting back the cause of young women who might want to pursue jobs in the City, including his own daughters.

The Ukip leader defended his comments, saying the gap in pay between men and women was just "the way the world works" because of biology. He said motherhood was a lifestyle choice.

Cooper said Farage was "talking out of his bottom" for saying there was no discrimination against women in the world of finance.