I’m not nasty piece of work, Boris insists

In an interview with the BBC’s Eddie Mair, a clearly uncomfortable Mr Johnson was forced to deny being a “nasty piece of work” and refused to discuss allegations about his private life.

The intense exchanges came after the Tory politician agreed to take part in an in-depth documentary about his life, due to be aired by the corporation at 9pm today.

Mr Johnson suggested he had been effectively “blackmailed” into participating by respected journalist Michael Cockerell.

“It is like when the News of the World ring up and they say listen, you are going to be in this story. You can either cooperate or not cooperate,” he said.

“I thought on the whole it was probably wiser given that it was going to happen anyway to try to say something rather than leave the field clear to put the boot in.”

When Mr Mair said he wanted to “talk about you”, the Mayor joked: “That’s exactly what I am trying to avoid.”

However, he appeared thrown as the interviewer grilled him on his sacking from The Times more than two decades ago for making up a quote.

“I mildly sandpapered something someone had said. It is very embarrassing, and I am very sorry about it,” Mr Johnson said.

Mr Mair, standing in for Andrew Marr on his Sunday morning show, then pressed Mr Johnson over whether he lied to Tory leader Michael Howard about allegations of an extra-marital affair in 2004,which resulted in his resignation as Shadow Arts Minister. “I never had any conversation with Michael Howard about that matter,” the Mayor replied. “I do not propose to go into all that again. Why should I? I’ve been through it a lot. ”

Mr Johnson said: “It is a measure of the trivialisation of politics that I thought I was coming on to talk about the Budget and housing in London, and you have... I do not mind all these questions about other stuff, but I think it is more important that we look at the things that are happening now in the economy and what the Government is doing to help.

Asked if he was going to watch the TV documentary, Mr Johnson said: “I’m certainly not, not after what you have told me. I am not going to watch it.”