Boris Johnson today said Eddie Mair had done a "splendid job" during an interview in which the Mayor of London was grilled over his "integrity", including suggestions he had lied about having an extra-marital affair.

In the interview with the Scottish broadcaster on the Andrew Marr Show yesterday, a clearly uncomfortable Mr Johnson was forced to deny being a "nasty piece of work'' and refused to discuss allegations about his private life.

Speaking in London today, Mr Johnson said: "Eddie Mair did a splendid job. There is no doubt that is what the BBC is for - holding us to account.

"I fully concede it wasn't my most blistering performance, but that was basically because I was set to talk about the Olympics and housing in London and he wanted to talk about other things, some of them - my private life and so on - of quite some antiquity, the details of which I wasn't brilliant on.

"He was perfectly within his rights to have a bash at me - in fact it would have been shocking if he hadn't. If a BBC presenter can't attack a nasty Tory politician, what's the world coming to?"

Asked whether Mr Mair should get Jeremy Paxman's lead anchor role on Newsnight, he added: "I should think he'll get an Oscar, it was an Oscar-winning performance. I think he'll get a Pulitzer."

Mair, 47, originally from Dundee and a former presenter of Good Morning Scotland and Reporting Scotland, also interviewed First Minister Alex Salmond during the show on Sunday.