Tom Baker walks into a central London hotel bar wielding a walking stick, dismissing journalists as traitors and uttering emphatic expletives. He is a big man, tall and well-built, with a good head of white hair. He doesn't want to sit in a quiet corner but rather in the thick of it, where he can "see human life". He slides into a faux-leather armchair, catches the waiter's attention and orders a drink in his deep, resonant, theatrical voice. "A Bombardier, thank-you, sir."

The beer arrives and Baker pours it carefully into a pint glass. "Good health to you. Nice to see you." Here is an actor still going strong at the grand age of 72; in fact, he is enjoying a renaissance late in life. He may always be best remembered for being one of the popular incarnations of Doctor Who (between 1974 and 1981) but in recent years Baker has become highly fashionable again. After a few decades of cameo roles in various modern TV comedies, Baker became the narrator in the phenomenally successful ­Little Britain.

He is not quite ready, however, to discuss his work. Instead, he takes a moment to enjoy the drink then produces a copy of Philip Roth's novel Everyman and waves it in the air. "I'm getting deeper and deeper into this new Roth. God, it's so sad. So, so sad. He's 74, I think. Usually his novels are much bigger than this. It's a meditation on death. When people don't have any religious faith, death becomes obscene."

He barely pauses for breath. "This bar is a good place to meet a pal. [In] the pubs round here it's hard to finish a sentence without some tosser from the BBC saying 'Tom! Do you remember doing some programme or other with me?' Or some girl saying 'Don't you remember me, Tom. We used to be married?'" He peers at me across the table. "Anyway, why are you interested in ballet, may I ask?"

Baker is in London to promote English National Ballet's new production of Oscar Wilde's The Canterville Ghost, for which he has provided a recorded narration. But I suppose the honest answer is that we are interested in Tom Baker. As a 10-year-old in the late 1970s, I never quite got used to seeing him walking around Hyde Park with his children, wearing an overcoat and the long, multi-coloured scarf he so famously wore as Doctor Who.

It's been a while since Baker lived in London. For the past four years he's been living in a village outside Toulouse with Sue Gerrard, who was an assistant editor on Doctor Who and has been his wife for more than two decades. He loves living in France and speaks the language well enough to make daft jokes (always ordering "une braguette" - a trouser zipper - in the local patisserie) but finds himself yearning for nuances of English.

I ask if he also misses his children and he snorts with laughter. "Bugger my children! Christ, they are middle-aged men. What do I care about them?"

It is quite hard to elicit a straight answer from Baker, who rambles on, avoiding questions and telling tall stories. In fact, it's almost impossible to interrupt his flow. After just 10 minutes, he mutters to himself "I know you've trapped me into this, so I'll give you a few more minutes" but is still going strong an hour later. Brusque and vague though he may be, Baker is also bright, charming and affable. Perhaps he is ­making the most of his opportunity to speak English. As soon as the tape is turned off he bombards me with questions. It is as though his one-man show is over and he can enter into a dialogue.

When I manage to ask if his wife is French or English he gravely replies: "She's English. I think. I don't pry. I was sitting on the phone once, bored, and started flicking through her passport. I'd been using the wrong name for 26 years. I'd been calling her Dorothy but her name was Sue."

A little later, he wistfully talks about the old school house in Kent he sold to comedian Vic Reeves. "I've got my gravestone all marked up in the adjacent graveyard. I caught a man putting forget-me-nots on my grave once as I was mowing the lawn. It was so sad."

Despite his white hair and walking stick (he has a pinched cartilage in his knee), Baker has no intention of stopping work, of giving in to old age. He says, quite simply, that he works because "it amuses me to do so". It's the only time he meets people. "Otherwise I might as well be a Trappist monk in France." Which would be life turning full circle, I manage to say, referring to the six years he spent as a monk on Jersey after leaving school in Liverpool at 15. "Yes, but I was never in the silent order - that would have been very severe." And virtually impossible.

Baker visits London regularly to do a range of different jobs. His distinctive voice has always guaranteed a decent income: he has done voice-overs for adverts for years and now does commentaries for presentations given by big companies. And since he narrated the links between sketches on all three series of Little Britain he has become famous to a new generation - but his work still comes from the original fans of Doctor Who.

"I'm now mostly employed by the children who watched me. I really am! Whether it's Little Britain or Monarch of the Glen . . . I get offered a lot but I really can't be bothered much. People always want me to do bold, slightly barmy commentaries."

Earlier this year he had a three-month contract to be the voice of BT's talking text message service. It has now expired. Baker spent 11 days recording 11,593 phrases and sounds that engineers then spent five months processing. Given his fondness for expletives and being a bit naughty, Baker loved the public's response.

"I got calls from girls ­saying 'That was a lovely, succulent, dirty message you sent me.' Haha! And some chap stopped me in Cavendish Square last week to tell me that in those three months 10m text ­messages were sent. I wish I'd asked for a penny a call instead of a flat fee . . . "

Although pleased to be busy, Baker also spends a long time complaining about the people who give him work, saying they stifle his creativity and make him sound banal. "I was looking at the script of The Canterville Ghost recently and it was just so ordinary and plonking. So, while I was resting my leg in bed, I decided to write some jokes, which I think Oscar Wilde would have appreciated because he and I used to be a couple. Sort of. Imaginatively. I've played him on two occasions."

The people at ENB ("they're darlings") did not take up his suggestions so the script, according to Baker, remains "ponderous, unspeakable, literary English, circa 1895".

However, he does have nice things to say about ­people too. He pays no attention to my questions about Little Britain's occasional lack of taste, saying instead: "The boys [Matt Lucas and David Walliams] are so lovely to be with."

When I ask about Christopher Ecclestone and David Tennant as the most recent incarnations of Doctor Who, he says: "I always get sweet messages - not from Christopher Ecclestone, who I was very surprised to see leave so soon; he's a very powerful actor - but from the little chap. David what? Oh yes, Tennant. When I was in Monarch of the Glen, a make-up artist friend of his asked me to send him a card, which I did. He sounds very sweet."

Whenever he's in London, Tom Baker is stopped in the street by fans of Doctor Who. Is it a relief to escape to France? "It doesn't drive me mad. People are willing to share things with me because they think they love me. Fan love is quite different because it endures. When I used to see a disintegrating George Best or some great old cricket player like Denis Compton, the nostalgia would always catapult me back to my youth. People who talk to me in the street make quite affecting little speeches about what I meant to them. There are plenty of actors more distinguished then I am but I bet that never happens to them."

In fact, Tom Baker's body of work is more impressive than you might imagine. Since joining the National Theatre in the late 1960s, he's worked with the likes of Laurence Olivier, Anthony Hopkins and Maggie Smith. In 1972, a few years before becoming Doctor Who, he also appeared in Pier Paolo Pasolini's version of The Canterbury Tales. What was the great director like?

Baker smiles. "He was wonderful. He was a terribly handsome man but not big. He was absolutely serene and mischievous. He didn't speak much English, so we had to use a translator. He wanted me to play the innocent and strip off. He said: 'It will be pornographic when we do it, Tom, but when I cut it, it will become art.' " He roars with laughter again. "He liked rough trade but he was absolutely lovely."

For those of us who missed him in television programmes such as Monarch of the Glen or Medics, it seems Tom Baker has had his renaissance late in life with one of the most popular comedies of the past decade. He doesn't know if there'll be another series of Little Britain - Lucas and Walliams are saying no to that idea just now - but he's busy enough visiting London for the odd day to lend his voice to all those frustratingly banal scripts.

Would Baker like to be offered a part in the new Doctor Who? He shrugs. "I've done my time but if the BBC had any bloody flair, if they had real genius, they'd have brought me back to play the Master." He seems a little hurt that no one has even offered a cameo and, as is his style, quickly moves on to something else.

"I've always wanted to play a vicar or judge who has Tourette's syndrome. We drove through the town of Tourrettes recently on our way back from the garden centre. I shouted out 'Shit! Arse!' My wife said: 'Is there no limit to being impressionable?'"

He laughs hard and long. Composing himself, he suddenly looks serious. He wonders how much use the interview has been, if he's said anything worth printing. He doesn't seem remotely worried, just curious. He leans forward in his chair and, for a moment, looks very serious. "Just make some stuff up. I don't mind, really." He lifts his glass. "To your good health."

'The Canterville Ghost' is at the New Wimbledon Theatre, London from May 25 to June 3