ARTS / Show People: Casting off the rakish image: Bill Nighy

BILL NIGHY is an elegant bag of bones in a grey two-piece, open-necked check shirt and a blond Chekhovian beard. You'd never guess he was also a bag of nerves. But he hasn't stopped squirming in his chair since, in an effort to break the ice, I told him how I couldn't imagine anyone else playing Bernard Nightingale, the preening Byronist in Tom Stoppard's Arcadia. 'I'm not very used to all this,' he apologises in that brittle voice, with Rs that are not far from Ws, at the end of another tortuously baroque answer. 'I'm not a very practised . . .' and another unfinished sentence twirls off frailly into the Peggy Ashcroft sponsors' suite at the National, like the curlicues of smoke from one of the six or seven cigarettes he smokes in the hour.

At 42, Nighy's critical rating, like that of his fellow Arcadia stars Emma Fielding and Rufus Sewell, has never been higher. This week at the Olivier he opens in The Seagull as Tregorin, with Dame Judi Dench as Arkadina, and we can safely bank on further updates from his work in progress: the rake.

The neurosis doesn't appear to be a straight case of inverted luvviedom - the 'I'm-so-nervous-tell-me-I-was-fab' school of drama queens. He's far too unimpressed with himself to play such games. But you don't need to put the patient on a couch to hit on some likely causes. Nighy (pronounced Nigh) was born and brought up in Caterham on the fringes of south London. His parents were working- class but, wanting the best for him, sent him to the Catholic grammar in Purley. 'To be thrown in with the middle classes at 11 is a massive thing to have happen to you. The summer before I went I got pains in my legs and I remember my father (a motor mechanic) saying: 'Oh that'll be the school - you don't have to go if you don't want to.' '

He went, and ditched his glottal stops 'as soon as I got there'. He remembers being 'desperate to please'. One report said: 'If Bill devoted as much of his energy to his work as he does to attempting to entertain the rest of the classroom, perhaps we'd see some results.' He never sat his O-levels, took off to Paris and, after a stint as a messenger on The Field - the closest the Job Centre could get to fulfilling his dream of being an author - he applied for drama school only because his girlfriend did it for him.

Nighy had acted at school but had only seen two plays - a Brian Rix farce and the RSC's all-male As You Like It. In his audition, 'I humiliated myself' by reading two female parts - Eliza Doolittle, and Cesario, whom he thought was male. He felt out of place, although on leaving had done well enough to land a six-line part in a Tennessee Williams' play in Newbury, but he still fetched up flogging women's clothes in Camden Market.

A long period at the Everyman in Liverpool, where the writers-in-residence were Willy Russell and Alan Bleasdale, gave Nighy his first extended introduction to the theatre. He nursed minor worries, like still not knowing left from right, but 'the major problem was acting and being any good at it. There were so many talented people there - you could tell, because they thought it was important enough to do brave stuff on the spot right there in rehearsal rooms. That made me feel disqualified a bit, but I hung on in there and I had a wonderful time there, except for my anxiety, which was terrific.'

His anxiety taught him to take nothing seriously, because 'if you turn up impersonating somebody who might want to be an actor but doesn't take it terribly seriously then people might be kinder when they tell you it's not going to work out . . . My reality was that I shouldn't be there and any minute they would ask me to leave.' But it did work out, no one asked him to leave, and nowadays Nighy has earned the right to an insouciance that is more than skin-deep.

After sterling work at the National - in David Hare's A Map of the World (where he met his wife, Diana Quick), as Eaton Sylvester in Pravda and Edgar in King Lear, both opposite Anthony Hopkins - he secured better and better parts in television. For a while, when The Men's Room was enraging male viewers with its unflattering portrayal of the unfair sex, Nighy's posterior was the most famous in the country.

Mark Carleton, the dishy academic suffering from 'lost puppy syndrome', was a far cry from Nighy's television debut as third bankrobber in Softly Softly Task Force. 'In my early career I only ever played below-stairs characters,' he says. 'I now embody a legitimate member of the middle classes.' Needless to say, he never watches himself on the box. 'I don't get paid to have to watch it. I have enough trouble being there. Maybe I'll get better at that.'

Maybe. But right now he even frets when you pay him the compliment, as I did, that he has managed to make a part his own. 'When other people say, 'Perfect casting', that really puts the wind up you because you're the only one who doesn't know why. You go away and ask yourself: 'What bit of me is perfect for this job?' And nobody tells you.' Unlike Bernard, there's nothing remotely rakish or swaggering about Nighy, so he must have been acting his socks off to appear so perfectly cast. On the evidence of this off-stage performance, he was born to play Sir Andrew Aguecheek. Best not to tell him, though.

'The Seagull': Olivier, SE1, 071-928 2252, previews from Fri, opens 7 July.