David Dimbleby: The Presenter Royal

It's been a long time since the BBC had to apologise for David Dimbleby – but it did once happen. Very early in his career Dimbleby was hired to commentate on a visit to Britain by Richard Nixon, a grand state occasion that the then youthful broadcaster took as the opportunity for some acidulous remarks about staged photo-opportunities and Downing Street news management. He apparently described the Prime Minister as "hogging the limelight", an observation that was almost certainly true but broke with the decorous conventions of the time. The result was a period on the bench as far as live commentary went. In an almost unique miscalculation of what the medium – or at least the BBC – could bear, Dimbleby had run a little ahead of the times.

Now, though, the tale can only figure as the exception that proves the rule. After the last few days BBC executives are bound to be a little twitchy about Tuesday's live broadcast of the Queen Mother's funeral – a Becher's Brook of sentimental nicety – but wayward impulses from their chosen jockey will be the very last thing making them fretful. David Dimbleby is now the safest pair of hands in the business – and uniquely fitted for this occasion by the fact that he is, in rather valuable ways, just a tiny bit behind the times. A Dimbleby broadcast takes you back to an era when a kind of sacerdotal trust attached to famous television presenters and when that shamelessly abused concept – the voice of the nation – was occasionally bodied forth by a single familiar voice.

It does that in part, of course, because the name has been around much longer than he has. And while it's easy to get this element of his career out of proportion (for most viewers today the name Dimbleby automatically means David or Jonathan, rather than Richard), it's clear that if anyone was born to the priesthood, he was. Indeed his presence in the studio next week might almost seem to have a constitutional force to it – as if the immemorial protocols of royal interment demand a Dimbleby at the microphone. Just as some grand families will expect a privileged position in the Abbey, this family can be quietly confident that a space has been reserved for it in the Outside Broadcast van.

Next Tuesday, Jonathan will be covering the event for ITV while his older brother holds court on BBC. Dimbleby himself can get a little testy about the suggestion that his stature as a broadcaster is some form of genetic inheritance: "I don't recognise that there is such a thing as a Dimbleby," he said once. But he's honest enough to acknowledge that other people might – and that his lineage wasn't exactly a handicap when it came to establishing his career as a journalist.

The media connection stretches further back than his father's long monopoly on state occasions because the Dimblebys were already a media family before television or radio came into existence – they owned a small chain of local newspapers which, on Richard's death, was passed on to his children. David bought out his fellow shareholders and ran the business himself for many years, an enterprise that gave him a crucial independence from the patronage of BBC bosses (he once described the business as a place "where nobody can sack me and nobody can haul me over the coals") but which also delivered its fair share of trouble.

The National Union of Journalists complained that it wasn't just the name – Dimbleby and Sons – that was Dickensian; that the proprietor's zeal for economy and thrift led to employment practices that were outdated and even exploitative. Last year Dimbleby sold the group to an American newspaper company for around £12m – a sum large enough to cushion him from executive asperities for the rest of his life. He works now because he has a continuing passion for public-service broadcasting, not because he needs to.

The disputes with the NUJ – and the family business itself – were probably one source of the widespread belief that his politics are right of centre, though he has always taken care not to reveal any political affiliations. This, too, is a family tradition. When Lord Wyatt wrote in his memoirs that "everyone knew Richard was a Tory", David and Jonathan wrote a joint letter to The Times, not so much to scotch the suggestion, but to insist on their father's reticence in this matter. "Neither of us knew, none of his friends knew, none of his colleagues has ever claimed to know," they wrote. "It seems unlikely that he would have confided only in Lord Wyatt."

Similarly, though Dimbleby insists that he always uses his vote, he prefers to maintain the fiction that his allegiances are quite unknowable. At the BBC he was once nicknamed "the large small businessman", an epithet that he may even have originated himself and that perhaps gives some clue to his free-market politics. No one has ever suggested, though, that his private beliefs are reflected in his interviews. One of his proudest professional moments remains the celebrated pre-election interview with Margaret Thatcher in which she was obliged to apologise on air for using the words "drooling and drivelling" about those who criticised the social consequences of her policies.

Both the error and the immediate retraction were a tribute to Dimbleby's skills as an interviewer – he has an informal manner that does not make politicians brace defensively from the outset and a vigilance that ensures any slips do not pass by unnoticed. This flows from an unusual emulsion of assurance and professional anxiety. If popular myth can be trusted, he isn't the first celebrity to be discovered in flagrante with a Mars Bar, but he's probably the first to have turned it to his advantage so effectively. When a camera unexpectedly returned to him during a general election broadcast to find him effectively gagged by confectionery, he understood that this was not an embarrassment but a moment that pierced the barrier between broadcaster and audience.

"I enjoy trouble on air," he has said in the past – and it's not just because it is at such moments that his salary is demonstrably justified, but also because they restore some of the vitality of broadcasting. At the same time he's at pains to keep trouble to a minimum; he still writes the names of interviewees in large print on the top of his notes, a novice journalist's insurance against going blank while on air.

He learned such skills from the corporation, joining BBC Bristol when he left Christ Church, Oxford (where he studied philosophy). In fairly short order he had followed in some of his father's more significant footsteps – presenting Panorama, then the BBC's flagship current affairs series, and establishing himself as the first port of call when it came to election broadcasts. Perhaps because of his outside interests, though, he always remained semi-detached from the BBC: "I am not of the BBC but I have been working for it for 40 years," he said when applying for the chairmanship last year.

While colleagues speak glowingly of his professionalism and patience (he does not throw tantrums or exploit his almost aristocratic broadcasting status), others point out that he's not much of a mingler. "He's a cat that walks alone," says one, pointing out that he prefers to return to his family home on the Sussex downs rather than wind down in the BBC bars. He left his first wife Josceline Dimbleby in 1992, after an affair of several years standing with Belinda Giles, an independent television producer. The couple are now married and have a young son, a late addition to the three grown-up children he had with Josceline. It is with family friends that he prefers to socialise – rather than politicians or television celebrities.

That element of detachment may explain why a man so widely admired in professional terms has had to swallow an unusual number of professional disappointments. When Question Time was first launched on BBC, Dimbleby lost the presenter's job to Peter Sissons – then the subject of an assiduous corporation seduction – and he only finally secured the role after a widely reported "beauty contest" run-off with Jeremy Paxman. The selection of Dimbleby rather than his more abrasive colleague might have looked like a triumph for the royalist over the republican tendencies in BBC current affairs, but in practice Dimbleby has accentuated the democratic informality of the programme – encouraging the studio audiences to get stuck into their elected representatives.

It's clear that he still relishes the challenge of these sometimes volatile encounters, but on at least two occasions Dimbleby has pitched for jobs that would require him to set broadcasting aside entirely, the first time in 1987 when he was a runner for the position of BBC director general and the second, more recently, when his name was in the ring for the chairmanship. He lost the first to John Birt – of whose stewardship he became courteously but consistently critical – and the second to Gavyn Davies.

There may have been something almost like cultural nostalgia in these attempts to move into management and restore the Corporation's glories. When comparisons with his father are made, Dimbleby is quick to point out that the BBC no longer enjoys the supremacy it did when he was broadcasting. And it's difficult not to see in his own career the image of an endangered species in a dwindling habitat.

Question Time is important to the BBC, but not important enough to prevent it from being pushed ever later in the schedules (a source of some irritation for its chairman). What's more the heyday of political broadcasting, when every by-election was an event, has passed, temporarily at least. This leaves Dimbleby, the most talented public service broadcaster of his generation, looking a touch old-fashioned in his virtues. As one former colleague put it; "that line about Britain losing an empire without finding a role is not a bad description of where David stands".

Next Tuesday of course he has a role again – and it will be oddly appropriate that the last Empress of India is talked out by a broadcaster for whom duty and tradition are not just prompts on the autocue.

Born: 28 October 1938.

Family: Father, broadcaster Richard, and mother, Dilys.

Education: Charterhouse school, Christ Church College, Oxford.

Married: Josceline Rose Gaskel, one son and two daughters (divorced); Belinda Giles, one son.

Career: Reporter BBC Bristol, 1961; special correspondent, CBS News, New York 1966-8; chairman, The Dimbleby Talk-In, 1971-4; Panorama, 1974-7, 1980-2,1989-; chairman of BBC Question Time, 1994-; sold family newspaper business in 2001 for £12m.

Hobbies: Sailing – he is the owner of a gaffe-rigged boat.

Brothers: Jonathan, broadcaster, and Nicholas, a sculptor. He has a mutual pact of silence with Jonathan about their respective broadcasting careers.

Home: £1.5m house in Folkington, East Sussex.

He says: "I've never been ambitious. I've rather had ambition thrust upon me"; "I know no politicians. It's deliberate – I find it very embarrassing to meet them. I like politicians to be my victims".

They say: "He's a cat that walks alone" – a former colleague.