London mayor Boris Johnson's father Stanley has hit out at Eddie Mair's interview with his son on BBC1's Andrew Marr Show, labelling it a "disgusting" piece of journalism.

However, his son has conceded that Mair had done a "splendid job".

Johnson Jr's encounter with Mair on the Sunday morning show was labelled a "bicycle crash" – after the mayor's penchant for two-wheeled transport – and ended with Mair, presenter of Radio 4's PM programme, telling him: "You're a nasty piece of work, aren't you?"

Johnson Sr told London talk radio station LBC on Monday: "I thought Eddie Mair's interview was one of the most disgusting pieces of journalism I've listened to for a very long time. The BBC sank about as low as it could."

Johnson Sr told presenter Nick Ferrari: "His grilling people about their personal lives, accusing them of guilt by association, openly abusing them in a legitimate interview. Frankly, I don't know where we are coming to.

"I have no idea who Eddie Mair is or what he does. But frankly, there is such a thing as respecting the office, even if you don't respect the man and that did not come through."

Johnson Sr, a former Tory MEP, described Mair's interview as a "travesty" and suggested he would not have "openly abused" Labour leader Ed Miliband in the same way.

He said: "As for saying he thought Boris was a nasty piece of work, well, honestly. I don't know where Eddie Mair's politics come from but I suspect he would not have treated the leader of the Labour party in that way."

He said he felt "great anger" watching the interview on Sunday morning.

On the issue of Johnson Jr's misquote when he was a journalist at the Times, Johnson Sr said: "I know about that quote. This was Boris 25 years, 30 years ago, ringing up actually his godfather, a historian, and he got it wrong. He got what his godfather said wrong. Later on various things happened as a result of that, good heavens …

"If that's the worst you can dig up, something 30 years ago, most journalists I know make up quotes all the time and I don't think they go down the drain for it."

Asked why his son had looked uncomfortable during the interview, Johnson said: "He was told he was coming on to talk about issues which really matter to London. There are quite a lot of them he could have talked about … instead he dug up totally irrelevant things which have been dealt with ages and ages ago."

Johnson Sr said he believed the BBC had overstepped the mark, and added: "One of the issues Eddie Mair totally failed to address was the Leveson thing. The more I think about it, the more I think what a travesty that interview was, not of Boris but of good broadcasting standards."

But speaking in London on Monday, Johnson Jr 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 Mair should get Jeremy Paxman's lead anchor role on Newsnight, Johnson Jr added: "I should think he'll get an Oscar, it was an Oscar-winning performance. I think he'll get a Pulitzer."

Ferrari, speaking after Johnson Sr's appearance on his show this morning, said: "He was, as you would expect, a father defending his son.

"We did a phone call and it started off with people defending the BBC and saying he was fair game. But by the end more people said they supported Boris.

"All of the interview was seen as absolutely legitimate until the line about "nasty piece of work". It was felt by listeners that wasn't the role of the BBC reporter or interviewer to say that."

The BBC said it had received 384 complaints about the interview, which was watched by about 1.7 million viewers.

A spokesman for BBC News said: "We believe this was a fair interview which took in issues facing London and the wider political landscape as well as looking towards tonight's TV portrait programme [Boris Johnson: The Irresistible Rise by film-maker Michael Cockerell, which will air on BBC2 on Monday at 9pm].

"As the documentary is biographical exploring controversial episodes in the mayor's life was considered appropriate. Eddie's line of questioning attempted to elicit responses to direct questions that were not being answered."

During the course of the 15-minute interview, Johnson Jr admitted he had "sandpapered" quotes as a Times journalist, failed to deny he had lied to then Tory leader Michael Howard about an affair and conceded that he had humoured an old friend when he asked for a phone number in the knowledge that the friend intended to beat up the owner of it.

The video of the interview was one of the BBC's most-requested on-demand programmes on Sunday.

Mair is one of a number of guest hosts of the Sunday morning politics slot while presenter Andrew Marr recovers from a stroke.

BBC insiders said there was broad support for Mair's interview from within the corporation.

"It was sort of his style, he will just say those sort of things. Eddie Mair is very different to someone like Andrew Marr," said one BBC News journalist.

"Other people might have begun that line ["You're a nasty piece of work, aren't you?"] by saying "Some people might think …" But that's not his style, it's not the way he operates. He was physically very close to him, leaning right in and almost touching him."

Corporation insiders said Mair was justified in going into Johnson's background, and the historic accusations about him, because of the BBC2 documentary about his life, in which he had taken part, which airs tonight.

There were even questions within the BBC, given the scale of the response today, why it did not make more of the interview yesterday in its news bulletins.

"Most people [in BBC News] think it was a good interview and he did well. They were impressed that he managed to get through the bluster that normally sweeps interviewers away," said a source.

"That particular ["nasty piece of work"] line does look a bit odd if you pull it out in isolation but in context, if you watch the whole thing, it does seem justifiable."

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