Could I just finish? Humphrys faces a grilling in the Lords

The veteran journalist vehemently denied he allowed his personal opinion to influence his line of questioning and told the House of Lords Select Committee on BBC charter renewal that it was his job to hold those in power and government to account.

Baroness Gibson of Market Rasen said: "John Humphrys speaks more than the person he is interviewing. It is not good broad-casting, because you can't hear the answers of the person he is interviewing."

The committee's chairman, Lord Fowler, put it to Mr Humphrys that he enjoyed a good argument. The presenter said: "I would argue with anyone about anything ... If I weren't doing that, it would be disgraceful. I think it is not just desirable, but absolutely essential that you hold people in power to account for what they say and do. That's our job. It may mean you have to argue with them to develop that holding to account."

He said politicians are "pretty big boys and girls" and in the aftermath of a train crash he would give the Secretary of State for Transport a tougher ride than a victim or witness to the event. Pressed by the former Glasgow Cathcart MP, Lord Maxton, on why unelected journalists had the right to hold elected representatives to account, Mr Humphrys sounded a bit like one of his own interviewees, muttering: "If I could just finish the point."

Relishing a moment most politicians only dream about, Lord Maxton replied: "I'm allowed to let you finish, but you don't allow anyone else to finish. Why do you consistently interrupt [interviewees] and try to make them answer a different point than the one you asked about and often express an opinion about what they are saying?"

Mr Humphrys said: "I reject that entirely."

The Labour peer claimed Mr Humphrys had interrupted James Purnell, a minister in the Department for Culture, Media and Sport, that very morning, 10 seconds into an interview about music licensing in pubs.

Clearly stung by the accusation that he voiced his own opinions in interviews, Mr Humphrys returned to it later in the session, saying: "Stating an opinion; if one does that, it's reprehensible. I take issue with the accusation made earlier that I speak my views in interviews."

The presenter, who ran a farm in Wales for 10 years, admitted he had been the subject of complaints to the BBC over his interests in organic farming, but said he had been cleared because he disposed of any financial interest many years before.

"Although I have an acknowledged interest in organic farming, I would claim that I give as rigorous an interview to supporters of organic farming as I do to its opponents," he said.

Mr Humphrys also defended self-regulation of the BBC from attack by its commercial rivals and rejected calls for the BBC to be overseen by an external regulator, saying although it would give the appearance of transparency, in practice the present system of governors "worked pretty well".

Sitting alongside Mr Humphrys were his fellow broadcasting heavyweights Adam Boulton, political editor of Sky News, and Nick Robinson, who takes up his new post as BBC political editor in September,

Mr Boulton criticised the Government's Green Paper recommendation that the BBC's present board of governors should be replaced by a trust, saying the failure to appoint an external regulator could lead to a repeat of the Hutton affair.