#that description

It was his role as the slightly less meths-soaked half of the Withnail partnership that earned him his first real, enduring taste of fame. Bertie Aherne once accosted him at a function and asked "Is that the perfumed ponce?" "The Prime Minister of Ireland!" grins McGann, hugely. "It's great, isn't it?" And over the years there's been a peculiar symbiosis between Withnail and Who . Not only was McGann handed the Tardis key, but co-star Richard Griffiths - the portly, predatory Uncle Monty - was also offered the role of the Doctor. And now Richard E Grant, Withnail himself, has inherited the twin hearts in the BBC's online animated adventure, "Scream Of The Shalka".

"He's a case, isn't he?" smiles McGann. "He's a mate, and we talk about everything, but not once, to this day, has he even said, 'Oh by the way, I'm the Doctor...' It's curious. If they'd offered me a gig doing - what does he do, The Scarlet Pimpernel ? - if they'd offered me a gig doing that, I'd have rung him, just as a courtesy, and said, 'Look, they've offered me this...'"

Does he feel proprietorial? "Not at all. It says more about him than it does about me. I was out shopping, and my agent called me and said, 'Ring this BBC radio station. They want to talk to you about Richard.' I didn't have a clue what he was on about. I called my son and said 'Go on the net.' He got this website up and said, 'Look, there's Richard!' I said, 'What does it say?' 'It says he's the Ninth Doctor!' I just collapsed with laughter. I just wept. More from thinking, 'Does this guy know what he's doing?' Richard's impulsive, but Jesus..."

They also offered the role of the toon Time Lord to Robbie Williams. "Robbie Williams?" says McGann, almost choking on an olive. "Are they crazy?" And This Year's Love star Douglas Henshall. "Ah, I can see Dougie doing that. They just offer it to a haircut, don't they? 'Who's got long floppy hair?'"

Did McGann ever fear that the role was a poisoned chalice? Saving the universe every Saturday tends to typecast a fella. "Initially I was waiting for that to happen, but I was probably being pessimistic. But those considerations are kind of in the abstract when you're being offered a load of dough. It's a job decision. At the time I needed the money. If I learned one thing from this profession it's that you have to think short-term, because by definition, being self-employed, you don't know what's down the road. You can guess - Jesus, how do you think they'll be looking at this in ten years' time? How will posterity judge me? But you'd drive yourself nuts.

"To some people I'm still that Doctor Who actor. I get the piss taken out of me rotten by the stage crew at the theatre I'm working in. They're always asking me for a sonic screwdriver... But that's about the level of it. I don't care. It's funny. I can deal with that."

Mark, our photographer, asks if McGann minds having some informal conversational shots taken. "You know I hate it," he shifts, ruefully eyeing the lens. "So if I look like I'm hating it, don't blame me. Yeah, go on then."

The camera mosquitoes around McGann as talk turns to next year's long-wished prime time resurrection of Doctor Who . While the papers have everyone from Bill Nighy to Ricky Tomlinson waiting for a call from the BBC, a groundswell of Who fandom - not to mention the panting ladies of the internet's Paul McGann Estrogen Brigade - are convinced that the fleeting Eighth Doctor should finally have his due.

"I'm not being disingenuous now when I say that I've heard nothing," says McGann. "And I'm unlikely to hear anything, except that they'll probably ask me to go back and do the regeneration, which I'd be happy to do. But if I was them, I wouldn't pick me.

"I think if somebody wants it more - and again, this is purely, purely rumour, so this could be nonsense, but not only have I heard that David Warner is up for it, but he really wants to do it. And if that's the case then they should give it to him, because you can't beat that. You can't beat passion. While I'd be into it, I..." McGann pauses, cautiously. "I've got to be really careful what I say here... I might not have the same passion that Warner would, to be brutally honest, simply by dint of the fact that I've done it before. If I was to get offered it, then I would have to be absolutely certain, and I would have to seek guarantees, that I could do the things I wanted to do in 1996, approach it the way we thought we might before. It would be unfinished business."

So what would his Doctor be like, blessed with a second chance? McGann toys with his hair, his fingers interrogating a stray lock. "I'd be much more inclined towards the dark and the melancholic. He's only half-human, but human means the human condition. When I was offered it originally, we talked about a much darker version of the character. It was around the time that the whole Anne Rice thing was in the air, this idea of a sort of melancholy vampire, more gothic, which is what I was very much more drawn to.

"This was my first spat with (producer Philip) Segal. I said, 'Look, I ain't a comedian. I can do funny stuff, but I ain't a comedian. I ain't McCoy. That's not what I do. I can't camp around particularly well, either! Don't make me do it! I'm a dramatic actor!' He asked me how I wanted to play it. I thought, 'I'll try and put the fella off.' So I read up a bit and I said, 'I'm much more drawn to the darker side of this character. He's a maverick, a rebel, he was drummed off his own planet and look what happened, he's estranged from his family.' And I was thinking, 'Right, that'll put paid to it.' And the more I said, the more he started going, 'Yep... Yep... Sounds fantastic!'"

Not that McGann necessarily believes he's in with a chance of a second shot. "I'm not sure I'm that bankable," he muses. "I've worked a lot for the Beeb, and they're now being exhorted to be much more cut-throat and competitive, more like the independents. Maybe it's in order to justify the licence fee; I don't know. I've done a few things for the Beeb in the last couple of years that simply didn't work. They weren't any good. Whether you were any good in them is immaterial. If they don't work, you all get tarnished, when it should be the producers that are taken out and beaten up!"

And it's not only a question of proven star power. In 1974 a magnificent freak such as Tom Baker could walk away with the role he was born for. It's hard to imagine him even being considered in the youth-saturated, looks-obsessed climate of today's television.

"I don't know about that," counters McGann. "I've got a feeling that if they were to go for David Warner, as they're threatening to do, not only do I think it would be a fantastic move, because he's a wonderful actor, but I think it would also mean that they were trying to go for gravitas rather than looks."

Even McGann's casting seemed to be a nod to the concept of Gallifreyan eye-candy, though. "It matters, yeah. It really matters. But think about it - in choosing me to do it, if we assume that was the thinking behind it, or even partly the thinking behind it, 'Let's get someone younger and easier on the eye', well, that didn't work either! So try and get into the minds of them sitting at their board table. What did work? Patrick Troughton worked. Jon Pertwee worked. Tom Baker worked. Good, solid, believable, middle-aged, grey-haired fellas. That's what worked. So someone like David Warner, who's a fantastic actor, one of the best Hamlets ever, and nice and weird, nice and weird looking, the guy is tailor made. Or Bill Nighy, though he won't do it. I think Nighy has other fish to fry.

"As I see it, there's a burden to play clever. You have to be clever; he's a clever person. Although he might berate intellectuals in certain instances as inactive or useless, he is one - he's brilliantly clever and resourceful. You've got to talk him down sometimes. There's sometimes something quite adolescent about him. So if you can get a guy who's 60-odd to play him, it's even more pronounced. It's like Lear. This mad old bugger just railing against everything, even his own dwindling powers, whereas if you cast some 20-odd year old, it's just a bit light..."

McGann has been visibly discomfited by the constant attention of our camera. It was clearly a peripheral irritation, as if a silent but insistent child was tugging at his sleeve as he tried to talk. Now he's cracked. "Sorry, can you stop that?" he asks, half in exasperation, half in apology.

Mark stops the cycle of click-and-flash. "Most actors love it," he says, baffled. "Good luck to them," says McGann. "The movie camera isn't in your face. When you're working, you're trained to ignore it. If I'm ever asked to look straight down the lens on a movie, I can't do it. You'll have to kill me before I can do it. Stills photography? Hate it. Hate it. Even when I'm in character. If there's a stills photographer working in the room, I hate it. I can't stand it. I'm distracted. I can't work, knowing that there's somebody there with a camera. I was just the same as a kid. There's nothing mystical about it.

"I hate having me picture taken. I don't read about myself in the papers. I won't go on chat shows. Never done it. Cheese. Life's too short. We work hard enough as it is to be believable in the things that we do. I think a little bit of mystique is a good thing. It doesn't hurt. In the end, the best publicity you can have for yourself is good work."

A figure of mystery, then, elusive, unknowable, flitting between worlds, changing faces, vanishing before the bothersome questions begin. Perhaps it's still perfect casting after all.

Nick Setchfield