Tilda swims ahead in the deep end

It's not easy to pin down Tilda Swinton. Quite apart from a CV that includes eight films with the late Derek Jarman, a supreme gender-bending performance in Sally Potter's Orlando and transforming herself into a piece of live art by sleeping in a glass case for eight hours a day while on display in the Serpentine Gallery, there's the fact that Swinton actively discourages any attempt to label or categorise her.

So while her performance in the noir thriller The Deep End was the talk of Cannes earlier this year, she won't even admit that she's an actress.

"I'm in heavy disguise," claims Swinton in the ringing, uppermiddle-class tones you'd expect from a general's daughter. "I honestly don't feel like an actress. The more I've done it, the more I've realised what actors do and the life they live and the priorities they have, the more it's become clear to me that I'm not an actress." In which case, you might wonder why she's sitting in a Beverly Hills hotel suite discussing her latest movie. To be fair, though, Swinton doesn't come across like your average actress. Very fair, with green/blue eyes, she looks younger than her 40 years and is forthright, effusive and rather more light-hearted than most of the characters she's played on film or stage.

She prefers to be described as a "performer", and while she might be splitting hairs, if it leads to more work like The Deep End then no one will complain. The first film from directing duo Scott McGehee and David Siegel since their startling and ingenious 1993 debut, Suture, it sees her playing a suburban American mom trying to cover up her gay teenage son's involvement in a murder.

She doesn't think her character's actions are unusual for a housewife. "First and foremost she's a mother, and I think a lot of women find themselves taking on this sort of vibe, this absolute commitment to dealing with emergencies on a five-minute basis, whether it's doing the laundry, putting the roast on, hiding a body, or finding $50,000 in 24 hours. My flippant but kind-ofserious line for the film is, 'It's a mess, she's a mother, she clears it up.'" As the mother of three-yearold twins, Swinton presumably knows what's she talking about, but she denies that she took the part because she's a mum.

Nor does she see it as too different from her past work, despite the fact that since her debut in Caravaggio in 1986 most of her roles have been in defiantly noncommercial films. "It plays with a kind of realism that I haven't done much of before, but there was enough about it that was familiar to me: the basic themes of identity and expressing yourself," she points out. "It's just less clever-clever and less alienated, I suppose."

That seems to be a trend for her because she astounded many people by popping up in The Beach, as the leader of the commune who ends up seducing Leonardo DiCaprio's hapless backpacker. She'll also be seen with Tom Cruise in the forthcoming Vanilla Sky and in Adaptation, Spike Jonze's follow-up to Being John Malkovich. After so long outside the mainstream, has Swinton succumbed to the lure of studiosized pay packets? "This is an experiment for me," she says firmly. "It's a very interesting one and I'm finding it very rewarding, but it doesn't mean that I'm going to stop working in the way I've always worked. I couldn't possibly work this way exclusively, I'm not industrial in that way." Nevertheless, she's been scathing about Hollywood in the past and I always assumed that her live art piece, Maybe, was an unflattering comment on the nature of stardom.

"Well Maybe is so open, that's the whole point," demurs Swinton. "It's like a mirror, it doesn't exist until someone stands in front of it and projects on to it, and if that's what you find in it, then I wouldn't argue with that at all. But I can contribute a moment in Vanilla Sky while still living in the north of Scotland." Having performed Maybe in London and Rome, she's now planning to take it to Moscow and Tokyo. What does she think about when she's in that glass case? "I couldn't even begin to tell you," she smiles. "When I'm not doing it any more I'll tell you."

Her career started in conventional fashion. After reading English at Cambridge, she joined the RSC but left after an unrewarding year. It was then that she became a member of Derek Jarman's unofficial repertory company and he remains the biggest influence on her. "Working alongside him for eight years was just the greatest stroke of luck I can imagine because, apart from the fact that we were friends, he made a film-maker of everyone who worked with him."

Perhaps the finest moment in their collaboration was her anguished turn as Queen Isabella in Edward II; it won her the Best Actress award at the Venice Film Festival in 1992. Jarman, though, seems to have expected his actors to be extremely self-sufficient. "Derek didn't really direct anybody," says Swinton. "He knew what he liked when he saw or heard it, but he couldn't possibly tell you how to do it. You did have to draw on yourself." She's angry that the BFI, which funded Jarman's films, has abandoned its production wing. "It's not possible for film-makers who want to work in a non-commercial way to work in Britain any more. If I was coming in now, I don't know where I'd find my home."

Would she like to turn the clock back? "Back to the Eighties," she exclaims. "Can you believe I'm being nostalgic about the Eighties?" No, but then who'd have thought that you'd see Tilda Swinton in a Tom Cruise movie.