During the tail-end of the Labour party conference, Adam Boulton can be found sitting in the air-conditioned neutrality of the Hilton Manchester. It’s a remarkably bland space – all giant leather sofas, inoffensive flower displays and a breakfast area the size of an aircraft hangar – but an ideal domain for British broadcasting’s longest-serving politico.

This is Boulton’s 25th conference. Or 26th – he’s not sure. By the time we meet (at 8am) he has already done three live broadcasts on Sky, one of which included an interview with the prime minister. We settle down to coffee and biscuits, which he snaffles. Presumably his impressive girth is the result of too many biscuits in too many hotel foyers.

He gestures outside, drawing my attention to a junior minister struggling past in the snappy Mancunian wind. Yes, Boulton, 49, is in his element. Although studiously apolitical (he has not voted in a general election since 1979), he has spent his life in the Westminster village. His authoritative, seemingly spontaneous live broadcasts have documented all the big moments in British politics for the past 20 years and some of the minor ones – such as the time John Prescott clobbered a man who threw an egg at him.

Since 2006 he has been married to Anji Hunter, Tony Blair’s former “gatekeeper”, who ran Blair’s office from 1988 to 2001 and who was until last year director of communications at BP. One assumes that she must have been extremely helpful with anecdotes when Boulton sat down to write his new book about the Blair years, but he denies this: “She didn’t even read it until it was published.”

He insists that they have always been studiously professional about keeping work out of their home life. “But sometimes,” he admits, “I’d come home and tell her what was going on, and she’d say, ‘Oh, you dirty journos, that’s all nonsense’. And then 24 hours later she’d say, ‘You know that problem – what do you think about it?’ ” Boulton would tell her what the television steer might be and Anji would relay it to the prime minister. “I’m quite sure that on more than one occasion I was sold out,” says Boulton genially.

Surely, as a nosy journalist married to Blair’s former bag-carrier-in-chief, you must have yearned to know all the grisly details? For instance, Cherie Blair never quite saw eye to eye with Anji, did she? Rumour has it that Cherie’s dislike for the elegant, charming Hunter – a friend of Tony since their teenage years – is such that she can’t stand to be in the same room.

Earlier this month, at a housewarming party for the Blairs’ new £5.75m country abode, they apparently had to be separated after Cherie accused Hunter of being disapproving about her own recently published memoirs.

“Anji must speak for herself,” says Boulton, sidestepping the question, “but I’d say that she worked for Tony Blair and that included respecting and helping Tony Blair’s wife. Sometimes that help wasn’t gratefully received.”

Was there a huge argument at the party? “I don’t know.” Hmm.

In conversation he is reasonably charitable about the former prime minister’s wife, all things considered, having some sympathy with partners who have to take on such an undefined role: “I’m not saying she was a fantastic success . . . but it’s a very uncomfortable role.”

However, on the subject of Blair – although he calls him a “phenomenon” and was so recently his guest – Boulton is quite disrespectful, even launching the fantastic suggestion that he has had a facelift.

“Everyone thinks he’s had plastic surgery,” Boulton says confidently. “I don’t know. But I do think he’s become a master of the universe. He has moved up into the grade of the super-rich.”

Is Blair vain enough for a facelift?

“I think they all are.” In his book the former prime minister comes across as Machiavellian, a liar and overly impressed by celebrity – frankly, it’s a wonder that Boulton can look the man in the eye, let alone have invited him to his own wedding.

“Look, all of them are friends of my wife,” says Boulton, referring to the guest list for his London nuptials in 2006 at St James’s church, Piccadilly, which included Alastair Campbell, Charles Falconer and Derry Irvine as well as Blair. “They are close acquaintances . You should be polite with them, but they are not my friends in that sense.”

Which is an interesting insight into how wedding guest lists for the great and the good are composed.

“It’s closer to a relationship that most people have with colleagues in their office,” Boulton adds.

When he and Hunter embarked on their affair (allegedly during a press trip to Paris), both realised that not only would their respective marriages have to end, but so would Hunter’s job: “We both accept it would not have been possible had she stayed on.”

But if she hadn’t left her job, what would you have done – become a showbiz correspondent?

He laughs: “Well, I don’t know. What do they call us? Talent? The reason I’ve stayed in politics is because people have wanted me to stay in politics.” Something about this response makes me think that Boulton expected Hunter to jump first. “But, you know, the dynamic of it was that I knew she wanted to do something else in her life,” he says.

Probably because Cherie was so tricky. Would Anji work with her again?

“I don’t think it’s any secret that Tony Blair has offered jobs to almost all the people he has worked with in the past. None of the senior people – Alastair [Campbell], Jonathan [Powell] or Anji – have taken those jobs.”

Blair is an “antipolitician”, according to Boulton, a man who was never “sewn into the political process”. Plus, he is no intellectual; culture, Boulton says, “just doesn’t seem to do it” for Blair. He pauses: “Although he genuinely does know one Blur album from another.”

Blair seems to have started off so genially; he once invited a quartet of senior television political editors (BBC, ITN, Sky and Channel 4) for lunch at Chequers. After a tour of the pictures (during which he got Turner and Constable confused), Blair asked them: “How are we doing, then?”

The book concludes with the depiction of an angry and flustered Blair in some underground Iraqi bunker, shouting down journalists and refusing to speak to anyone on the return trip.

Can we now expect a memoir from Mrs Boulton? “Anji thinks that in most cases it’s improper for people [in the inner circle] to have done it – and they shouldn’t have done it.” (Are you reading this, Cherie?)

It’s amazing, really, that Anji and Tony are still friends.

What does Boulton think of The Ghost, the novel by Robert Harris that many took to be a roman à clef?

“Look, there are three characters clearly modelled on Tony, Cherie and Anji,” says Boulton, who knows very well that I’m thinking about the affair – in the novel – between the Anji character and the Tony character.

“The physical descriptions are very close. Once they start interacting with each other, it’s a different story. The Cherie character turns out to be a CIA agent and I’m not sure that’s the case in reality.”

Tell me, Adam: did your wife once have a teenage fling with the former prime minister? “I’m not really bothered about a fling,” says Boulton, with a smile. “This question has been delved into endlessly and they all say not, so not. But as with any of my partners, I have never been particularly bothered about their past life.”

Which, of course, is not quite a denial.

Tony’s Ten Years: Memories of the Blair Administration by Adam Boulton is published by Simon & Schuster on October 6 at £17.99

Times Recommends

• UK regional accents thrive against the odds
• ‘Scarecrow’ wind farms put rare birds to flight
• What an anti-climax: G-spot is a myth