Attack dog Humphrys hounds his BBC boss

John Humphrys, the veteran host of Radio 4's Today programme, accused the corporation of acting too slowly and failing to learn the lessons of previous crises, including the Hutton inquiry.

In a stuttering performance, Sir Michael admitted editorial controls had failed and parts of the BBC were still not taking them seriously. He was ambushed by Humphrys, who began the interview by bluntly saying that the Trust had "hardly covered itself in glory."

Sir Michael said: "We all know when a programme goes too far and clearly the Brand programme went too far."

He added: "Firstly, we are saying there is a need for further tightening of editorial control. There are still parts of the BBC where editorial responsibility is not being taken seriously enough. There need to be even stricter editorial controls where there is provocative material."

The Chairman also admitted that Ross had stepped out of line before after Humphrys accused the Trust of allowing standards to slip, bringing up comments made by Ross to David Cameron about whether he had fantasised over Lady Thatcher in an infamous interview from 2006.

Sir Michael admitted: "I don't believe comments like that should be made. But this is not a question of me defining where the boundary lies."

Humphrys retorted with: "We do that every time Sir Michael. We've had three scandals now in a few months and each time we tighten the editorial controls."

More than 20 people complained after Mr Ross asked the Tory leader: "Did you or did you not have a w**k thinking, Margaret Thatcher'?" The Corporation had previously stood by the decision to air the remark during the edition of Friday Night with Jonathan Ross in June 2006.

Sir Michael insisted in the heated interview today that he believed the BBC should not back away from provocative material, warning the corporation would fail to reach younger viewers if it did not represent changing attitudes.

But when he was criticised for failing to fill the remit of a public service broadcaster and of mistakenly chasing younger viewers rather than exerting a "civilising influence on the nation" he said: "The BBC Trust is in the process, and will next year address the updating of those guidelines, and we'll do that in conjunction with the public. But we won't back off the BBC's mission to serve everyone in the United Kingdom.

"There is a need for a clear understanding of where the boundaries lie, recognising that it's not a picket fence we can all point to. It is a matter of judgement and if it weren't a matter of judgement, frankly we wouldn't need editors and controllers."

Former Tory party chairman Lord Tebbit, who at the time criticised the David Cameron interview as "obscene", welcomed Sir Michael's stance. He said today: "It would have been much easier if they had cracked down and got rid of an overpaid oaf like Jonathan Ross long ago.

The row came as the BBC was criticised today for an offensive comment about the Queen on the BBC 2 satirical comedy programme Mock the Week. When asked to think of something the Queen would not say in her Christmas speech, Scottish comedian Frankie Boyle said: "I have had a few medical issues this year — I'm now so old that my p***y is haunted."

Tory MP David Davies called for the BBC to be held accountable for the remark, aired on Wednesday.

The BBC said today it had now received more than 35,000 complaints about the obscene messages left by Ross and Russell Brand on the answering machine of actor Andrew Sachs.