Yentob is a victim of his celebrity lifestyle, say BBC colleagues

His address book includes some of the best-known names in arts and entertainment. David Bowie and Charles Saatchi are personal friends, Anne Bancroft and Mel Brooks are godparents to his children.

In the grey world of the BBC executive, Alan Yentob is something of an exotic creature - combining boardroom clout with the media profile of a celebrity presenter.

So to BBC insiders it is no surprise he is a target for attack, nor that it has come in the form of allegations about his lifestyle.

On Friday, the BBC confirmed the new director-general Mark Thompson has authorised an internal investigation into Mr Yentob's expenses after allegations he used one of the corporation's chauffeur-driven cars for personal journeys and obtained upgrades to plane flights.

Friends and colleagues immediately rallied to his defence, claiming he is the victim of a smear campaign.

"Alan will always have had quite high expenses," said a senior colleague, "but that's because he's the best face of the BBC. The corporation desperately needs people like Alan around. He's worth his weight in gold."

Mr Yentob, 57, the head of entertainment, drama and children's programmes, has issued a flat denial of the allegations, describing them as "malicious".

He began work at the BBC in 1968 as a general trainee. Since, then he has held posts as producer and director of the arts programme Omnibus, controller of both BBC1 and BBC2 and head of music and arts.

Mr Yentob is credited as a major influence on British arts broadcasting. He devised the flagship BBC1 programme Imagine and raised eyebrows by taking the presenter's role himself - a move which has led to the programme being nicknamed "Al's Pals".

Two years ago, the corporation paid for an official Glastonbury Festival party at his Tudor mansion in Somerset, a cue for humour and criticism.

Mr Yentob was again the subject of criticism last year when he accepted a £20,000 bonus for his work on Imagine. Including the bonus, he took home a total pay package of £321,000 in 2003.

He will have been heartened by the backing of former director-general Greg Dyke who described him as an "enormous asset to the BBC". "I have always been a great fan of Alan's," Mr Dyke said. "Last year I recommended he receive a special bonus because of all the additional work he put in when Imagine was created." Mr Dyke said Mr Yentob had even "worked for free" to create and then present Imagine.

A senior and long-term BBC colleague said: "If you cut Alan in half you will find 'public service broadcasting' and 'BBC' written right through him. This isn't about diverting public funds. Alan's a very wealthy man - he doesn't need to take money from the BBC. I think it's bloody unfair. Alan has given his life to the BBC."

The row comes at a difficult time for the corporation, which on Tuesday will publish its annual accounts. On the same day, its executives are to appear before the parliamentary select committee for culture, media and sport.

A BBC spokesman said: "Concerns have been raised about Alan Yentob's use of expense budgets. The BBC's chairman, Michael Grade, and director general, Mark Thompson, agreed on Mr Thompson's arrival this was a management issue and Mr Thompson should take appropriate steps. Mr Thompson has asked the BBC's chief operating officer to examine these concerns and report back to him."

No other BBC executives appear to have been targeted, leading to speculation that the allegations are an attempt to destabilise Mr Yentob.

"I suspect it will turn out not to be true," said a senior TV executive, who suggested some senior BBC contracts permit the use of chauffeurs for private business. "He's not going to risk his career over expenses."

¿ Des Lynam is to work for the BBC again, it was announced yesterday. The presenter, who bowed out of ITV after Euro 2004, will host a Saturday radio show interviewing leading sports personalities from next month.

CASH AND THE CORPORATION

By Steve Bloomfield

John Birt

The "Armanigate" scandal engulfed the BBC's director-general in 1993 after this newspaper revealed he was employed via a one-man company, John Birt Productions. It was alleged that this substantially reduced Mr Birt's tax bill because he could claim personal expenditure, such as his £900 Armani suits, against tax. Mr Birt said it did nothing of the sort but quickly changed his employment status in an attempt to quell the story. BBC staff unions called for Mr Birt's resignation, but he remained in the post until 2000. Now Lord Birt, he advises the Prime Minister on everything from transport to the police.

Kevin Connolly and Graham Leach

In 1995 Tory MP Michael Fabricant tabled two motions in the House of Commons that named Mr Leach and Mr Connolly as being at the centre of "persistent stories" over large expenses bills. The MP alleged that expenses claimed by the BBC foreign correspondents included a lawnmower for a fifth-floor flat and airlifting a grand piano. There were claims for private education for children, even when they were in Britain, and office furniture that had mysteriously disappeared. A BBC spokesman denied all the allegations at the time. Mr Leach resigned before the allegations surfaced, while Mr Connolly moved from Moscow to Paris. Mr Leach is now a reporter for Sky News.

Andrew Gilligan

Mr Gilligan's infamous meeting with Dr David Kelly at the Charing Cross Hotel in central London cost the BBC £4.15 for a bottle of Coca-Cola and a bottle of Appletise. It was here that Dr Kelly allegedly told Mr Gilligan that the Government had "sexed up" the dossier on Iraq's weapons of mass destruction. The cost of the meeting was revealed during the Hutton inquiry when Mr Gilligan submitted the receipt as part of his evidence. Following the publication of Lord Hutton's report in January, Mr Gilligan left the BBC and now works for the Spectator magazine as a defence correspondent.

Ann Wilson

In February, she was sacked as managing director of BBC Technology for "misuse of hospitality" when entertaining corporate clients. Mark Byford, then acting director-general, announced her dismissal in an email to staff after an internal investigation.