'Blair has gone a bit mad'

He morphs from Tony Blair to Gordon Brown to his current favourite impersonation, Jeff Randall, the BBC's business editor. It's like watching him swim underwater. He takes a deep breath, goes down into a long monologue ("I'm not ranting, am I?") before coming up for another breath, then it's straight back down again.

"This nannying, they keep saying it's about choice but it's clearly not. I think they should marry the hunting thing with obesity and if they actually just turned fat people out into the countryside and asked people on horseback to chase them, that would be an answer." It probably wouldn't satisfy the thrill of the chase, though. Should they shoot them? "Only the really fat ones."

Bremner is worried that he's turning into a grumpy old man, but he's too energetic and enthusiastic for that. He is 42 ("I do feel myself getting older"), tall and more handsome than he looks on the telly. T

oday he is wearing black jeans and, nestling under a bit of a paunch, a large silver belt buckle - part Johnny Cash, part Richard Madeley. A typically fortysomething male accessory that says, "I've still got it (haven't I?)" or something he stole from the show's George W Bush dressing-up box?

He says he's very happy now but there was a long time when he wasn't. If the best comedians are supposed to have dark years of breakdowns, disastrous love affairs and crippling self-doubt, Bremner fits the cliché. It's been so well-documented-that when I bring it up, Bremner says, "Oh yeah, boring, boring. It was a long time ago."

Bremner was 25 when he married his first wife, Susie Davies, a teacher he met backstage when he was performing a stand-up show in Portsmouth. The marriage lasted eight years and they divorced in 1994. "I was far too young and it wasn't fair on either of us," he says. "I didn't know who I was then. I'm not sure I do now but I've got a better idea."

Back then, his life was shadowed by an eating disorder that made him lose two stone. "I just couldn't eat. I'd go to the fridge, open the door and then have to go upstairs and be sick because I couldn't even stand the smell of the food. My body image was very distorted."

Yet, while Bremner seemed to be withering emotionally and physically, his career was taking off. His divorce coincided with the start of his success on television and as a result, the break-up became rather public.

So did his subsequent relationships with other women, including Penny Smith, the television presenter, and Zoe Appleyard, an upmarket banker and friend of Jemima Khan. "I've never really put it about a lot," says Bremner, but for a while it looked that way.

Then, burned out, depressed and unhappy in his relationships, he went into therapy. Is he still seeing his therapist? "No, that was a specific time in my life when I needed it. I don't any more."

In 1999, he met Tessa Campbell Fraser, an artist whose sculptures were shown at this year's Royal Academy summer show. Within a year they were married, moved to Oxfordshire and soon after, their daughter Ava (now three) was on the way. They also have another daughter, Lila, who is one.

Is he happy being married? "Oh yes. The problem is, if you are working a lot, when you've got so much on, you can forget that you've got a wife and children who need you, too. Tessa finds that hard."

Bremner is trying to cut down his workload to spend more time with his children, even though he thrives on stress ("I need to be stressed just to get up in the morning").

He must be quite a fun dad. "I do try to make them laugh. Ava's favourite impression at the moment is somebody being hit over the head and falling over.

I find I'm doing the Michael Howard impression when I'm telling her off for trying to cut her sister's nose off with a pair of scissors. I can see myself in Michael Howard make-up, saying, 'I'm not going to hurt you'. Thank God she hasn't yet started associating me with him yet."

Yet despite the success, both in his private and professional life, he'll probably never get over the one thing that's obvious as soon as you meet him: his need to be liked by everyone. He says it comes from his mother.

"The only time I don't really care is when I'm being Michael Winner and actually, even then, I'm worried that it's not going well," he says. What worries him most? "The thought that I might let people down."

Bremner grew up in Morningside, the genteel Edinburgh suburb. His father was an Army major and Bremner was sent to boarding school at the age of eight. Unsurprisingly, given his talent for mimicry and being one of the sporty boys, he was very popular and a show-off. "It gave me a certain status," he says. "School - especially public school - can be a lonely experience."

He was a teenager studying at Wellington College when he learned, accidentally, after reading a letter lying open, that his father had cancer. By then Bremner senior had given up the Army to work as the appeals leader for a leading cancer charity; when he became ill, he was sacked. Rory was 18 when he died and was struck by the unfairness and injustice of it all.

The issue that is now firing him up the most is, of course, Iraq. "If the Blair of 1994 looked at the Blair of 2004, I imagine he'd be quite alarmed. He does the best impression of himself now, he's got it absolutely perfect: that fake sincerity, the false laugh and earnestness.

"If you were to look up 'goalpost movers' in the Yellow Pages, you would find there is only one and it's New Labour. They are like builders, Blair the Builder. You ask him to come round and fix the health service and he's off on another job in Iraq. You ring him up and say, 'Where the f*** are you? When you've actually finished doing a bathroom in Basra, can you come and mend the roof ?'"

Who does he dislike more, Bush or Blair? " Blair is bright enough to know better. Iraq was a bonkers idea but Blair seems to believe he was right. But that's the thing about Blair, he will believe anything he wants to believe at any given moment. I think he's running out of time and he's realising in his quieter moments that opportunities have been wasted.

"He's a man in a hurry. I don't think he'd like to go down in history as the prime minister who failed to tackle reform at home and took us into five wars and left Iraq and the Middle East in chaos.

"I think in his current state of mind he's a bit like Wayne Rooney." Because they both have sex with middle-aged women? "Ha ha ha!" he shouts. "No, it's because he is the most talented and the most capable of his generation but he's gone a bit mad, charging around lashing out at people and countries. He is mad, by certain definitions. The delusions, the distortion of reality - he ticks all those boxes."

Who will he vote for in the next general election? "I've voted for all three at different times. I cast my vote in a particular election in a particular way that I think would make the most difference, so I'd vote for the Lib Dems if they were coming a close second to the Conservatives."

He's exasperated with Blair but has a lot of respect for Gordon Brown. "I think he's a genuine, principled politician. I've admired what Robin Cook has said recently, I admire Ming Campbell of the Liberal Democrats."

Much of his material comes from meetings and lunches with politicians and advisers, but Bremner insists he's not friends with any politicians, no, not even Brown. "It makes me feel very dirty. It's a very obsessive world, these strange creatures running around with tremendous chips on their shoulders."

How about Alastair Campbell? Has Bremner tried to meet up with him? "God, no," he says. "Alastair Campbell's relationship with Blair is looking more and more like Paul Burrell's relationship with Diana. Just as Burrell has lived off Diana, Alastair Campbell is now living off the Prime Minister of People's Hearts. Campbell is Blair's Burrell. Ooh, that's rather good. Is it? Do you think? I think I might put that in the next series."

You Are Here, by Bremner, Bird and Fortune, is out now in hardback (£16.99, Weidenfeld & Nicholson). Rory Bremner is in conversation at the Orange Word event on Tuesday 30 November at 6-7pm at the Criterion Theatre, tickets £7. To book, visit www.orangeword.co.uk or call 0870 9901299.