Chalk it all up to experience

Think of an actor. Now think of a role they've played that you never dreamed was within their powers. It's not as easy as you'd imagine. Most actors are cast on the strength of what is known about them. The genuinely protean actor, whom you scarcely recognise from role to role, is a rarity. So before you ask, yes, that is David Bamber taking the lead in both Chalk, a hectic new sitcom on BBC1, and the muted, elegiac television version of my Night with Reg. In the one he plays a neo-Fascist teacher, a ticking time-bomb of barely suppressed spleen and thwarted ambition; in the other, he's a meekly disillusioned homosexual cast into shadow by the promiscuous, effervescent company he keeps.

Bamber won an Olivier for his role in My Night with Reg. It was presented to him by Raquel Welch, who was here to play Shaw's millionairess. Some of her ill luck must have rubbed off because, absurdly, apart from playing Captain Hook in Leeds, he hasn't been offered a single stage role since. What are all the casting directors playing at? He had long been admired for his diligent work in small but significant theatres when he was invited to play the oleaginous Mr Collins in Pride and Prejudice. The night after it was broadcast he was, as the phrase has it, a "name in the corridor" at the BBC. "I think what I was surprised at was the impact it had," he says. "That character seemed to get a lot of response. I suppose I'd been doing that sort of thing for a long time, it's just it had usually been in front of 50 people at the Bush." Sitcom scripts made their way to his agent, and Chalk, set in a secondary modern school, was the one he pulled out of the hat.

Bamber plays deputy head Eric Slatt, a diminutive dictator who has all but seized the reins of power from his flaky, liberal superior (John Wells). Slatt inherits all of Mr Collins's cynical opportunism but, being far more openly undermined, he is given to thunderclaps of rage which he is obliged by his position to try and control. Like all Steven Moffat's comedy - last year's The Office, a Carlton one-off starring Robert Lindsay as an executive whose day goes horrendously wrong, or Joking Apart, the BBC2 sitcom about a divorced man obsessed with his ex-wife - Chalk is in the idiom of sadistic farce: disaster begets catastrophe begets apocalypse, and they all engulf Slatt. There are inevitable echoes of other sitcom characters - a dash of Basil Fawlty's unquenchable apoplexy, a slice of Gordon Brittas's purblind monomania - but Slatt's entanglements are caused by his own cocktail of failings. In the particularly insane second episode, Slatt has convinced a blind school inspector that he is in fact a long- lost girlfriend, and naturally he is caught in the act of trying to prove it.

Turn now to My Night With Reg, the hot-ticket tragicomedy about the spectre of Aids, which writer Kevin Elyot and director Roger Michell recorded for posterity 18 months ago and turns up in the "Performance" season. There's a good deal of all-male kissing here too, but it's mostly polite, puckered pecking between consenting cruisers. Bamber plays Guy, who invites everybody back to his flat after Reg's funeral only to receive consecutive confessions from his guests that they all slept with the deceased. Although he had a boyfriend in publishing, Reg's most frequent conquest was Jack- a beefy, bed-hopping lounger for whom Guy has always had a unrequited pash. It is out of this unequal, unfulfilled relationship that Bamber has invented for Guy an array of exquisite, feminine movements, mainly of the neck and hands, on many of which Michell lingers in sensuous close-up. "Guy was being watched a lot of the time," says Bamber of his character's genesis in rehearsal, "and so he became very self-conscious. He felt that Jack was always watching him, so even if he sat down... If you imagine having your favourite film star in the room the whole time, it was like that. He was so aware of the scrutiny, and also the embarrassment of that scrutiny, and the delight of it at the same time."

It's a signature of Bamber's performances that he arrives at these physical decisions by a combination of intellect and instinct. He can explain why his characters do what they do but there comes a point where he is as much guided by them as they by him. "If you're getting the character right," he says, "you're not aware of the subtle body changes." Thus it looks wholly organic that Slatt's arms should be lashed to his sides, in a physical expression of his huge effort at self-control. Bamber also has a peculiarly expressive neck, longer than it ought to be for someone of his height (no more than 5ft 6in), with which he can convey everything from modesty to sadness.

Like Ken Stott, he seems to have hit his stride around the 40 mark, an age when there are no more Greek God roles going. "When you do have great looks, film is very kind and there's a career to be had in your twenties... Clearly it does matter what you look like. But often people ask actors, `Why do you always choose those outsider parts?' And you think, but everybody knows they're the best ones. The one where the hero says to somebody, `My best friend is coming tonight. Don't be shocked but he's got half his face missing.' That's the part to have."

Bamber encourages this perception of his own difference with an entertaining line in self-deprecation. He had his first taste of rejection when he failed his 11-plus, and expectations palpably lowered. He got a place at a college that would have trained him to teach drama to children with special needs, but at the last minute he read drama at Bristol instead, and only after that did he go to Rada on a scholarship. His classical training found him "frequently drinking out of goblets with a sword in the other hand. I remember thinking, `I'm dying to drink coffee on stage and sit on sofas and things.' " He's done far more drinking from cups than goblets since leaving. He did play Horatio at the National, but that was when Daniel Day-Lewis had his breakdown during Hamlet. In Peter Hall's Oresteia, "Tony Robinson and I were the only two people in the entire company who didn't have any role. We were going to do alternate performances as the younger Clytemnestra, and then one famous rehearsal Peter Hall called us in and put his arms round us and commiserated. We ended up just doing the chorus."

Robinson, of course, went on to sitcom apotheosis as Baldrick, and Bamber may now be about to follow suit. Chalk looks to have legs, and the BBC have sensibly given it a second series to carry on finding its feet. "It's a very extreme kind of show. I think it will take a bit of time to tune into it. With the episode with the blind school inspector, the director said to me, `Now probably tonight nobody will laugh for 15 minutes'. And we started and they were laughing. And over the course of the weeks, I think we became moderately funny ourselves, but it was in the writing; the gags were there. They knew exactly what Steven Moffat was doing and they laughed right from the top of the show."

Episode 1 of `Chalk' is repeated at 11.55pm tonight on BBC1; Episode 2 is on Thursday at 9.35pm (repeated the following Sat)

Performance, `My Night with Reg' screened 10pm Sat 15 Mar, BBC2