What makes Tilda Swinton such a uniquely paradoxical screen presence? Simply this: she seems not altogether of this earth, yet she can be more downright earthy, even grubby, than just about any screen personality you can name.
Film-makers have long valued Swinton's other-worldly characteristics - her glassy, rarefied quality, the translucence of her facial features. Early in her career, she played a robot visiting Earth in the 1987 film Friendship's Death; then hovered between sexes and time frames in Sally Potter's 1992 adaptation of Virginia Woolf's Orlando. More recently, she was an archangel in pinstripes in the Hollywood fantasy Constantine.
That's the eerie, ethereal Swinton. But she can be gritty too: a surly biker dame in Jim Jarmusch's Broken Flowers; a roaring, sewer-mouthed doyenne of London's demi-monde in Love Is the Devil, John Maybury's 1998 portrait of Francis Bacon. She also, now that she's a Hollywood star of sorts, did what you can't imagine many Hollywood women doing: she appeared in last year's corporate thriller Michael Clayton, with sweaty armpits soaking through her ostensibly ice-cool executive blouse. That sweat, and that nerve, contributed to a Best Supporting Actress award at this year's Oscars.
Tilda Swinton is surely the most elusive and malleable personality on screen today, yet is unnervingly no-nonsense about what she does. What interests her in film-making, she tells me when I meet her, "is so much less than acting - it's dressing up and playing and being in communication with the director, and that's it." Recent years have brought ample opportunity to dress up, Swinton's sveltely enigmatic looks making her a fashion muse to designers including Hussein Chalayan and Viktor and Rolf. Even seated over tea at Claridge's, she could be a living installation piece: pale composed face, short hair swept back in a boyish flop, and wearing a gleaming white Vivienne Westwood blouse that's all angles and flaps, so that she resembles a Vorticist portrait or a complex piece of origami.
Swinton, now 48, has an aura of grandness, rather than grandeur, about her: a confidently upper-crust English accent that you suspect she's almost playing for laughs, and a crisply articulate way with words. You don't normally think of her as being one for comedy - although her cut-glass Washington virago in the Coen Brothers' screwball Burn After Reading was one of the year's surprises. Yet Swinton once claimed that she saw herself as more a clown than anything else.
"That's more accurate than 'actress'," she says. "I think I'm funny a lot of the time - but other people don't see it. Maybe people get put off by tall people with serious expressions. But Buster Keaton was very funny, and he didn't laugh much." Maybe, she speculates, it's because her early work with her mentor and discoverer Derek Jarman was seen as terribly serious; but even with him, she did comic parts, she points out. "I love this," she says, "me pleading for you to admit that I was once funny," and lets out a raucous cackling laugh.
Swinton insists she's clowning even in her new film Julia, an emotionally gruelling portrait of a Los Angeles drunk. Again, she hits the outer edges of earthiness in the title role: she's first seen staggering round a barroom in high heels and glitter eyelashes, then emerging from her car the next morning, sweaty, fleshy, dishevelled and in raucously mean spirits as she discards a used lover.
In constrast to Swinton's recent high-profile US films - which include David Fincher's forthcoming The Curious Case of Benjamin Button, opposite Brad Pitt - Julia was made on a low budget in classically frantic indie-film circumstances, after severe budget cuts ."Shooting 17-hour days over six-day weeks, everybody with dysentery - it made that film." The director was Erick Zonca, the Frenchman behind the acclaimed The Dream Life of Angels in 1998. Swinton had previously met him in Cannes at an official party to which they were both refused admission: "It became hilarious, and it involved trying to storm the door with a fire extinguisher. I was left with a memory of a very jolly individual, and then I saw his films."
Zonca proved something of a wild man on set, showing Swinton a line of moving traffic on a motorway and telling her to rush across it, no questions asked. She responded to a pitch of intensity in both the director and her character, connecting with ideas she had already had about playing an alcoholic, to do with capturing "the kind of inventiveness and imagination and energy and courage and va-va-voom that I recognised in all the drunks I've known." All that, she feels, comes across in the very feel of Julia: "It's not that we made a film about an alcoholic but that we made an alcoholic film."
Swinton's other new release is darker still: The Man From London, a hyper-severe Georges Simenon adaptation by the legendarily sombre Hungarian maestro Bela Tarr, whose work an enthusiastic Swinton has described as "mediaeval". "It feels to me as if these films were dug up out of some tomb in Transylvania and they've always been there. It's not about being timeless exactly, it's about being ancient."
Of course, you expect to find Swinton working with challenging, off-mainstream directors such as Tarr and Zonca. These days, however, what's surprising about Swinton's CV is how many big-name US productions it includes. Her embrace of the mainstream can be traced back to 2000, when she appeared opposite Leonardo DiCaprio in Danny Boyle's The Beach. Overnight, high-profile roles started to crop up: the Tom Cruise vehicle Vanilla Sky, Spike Jonze's self-deconstructing farce Adaptation; and, most spectacular and improbable of all, the Disney-produced The Lion, The Witch and the Wardrobe, with Swinton as a supremely glacial White Witch. She took that part, she says, partly "for Derek Jarman's sake, because of his great attachment to screen witches. What Disney doesn't necessarily acknowledge is that little children love that witch - and most of them think the wrong side won."
I've never yet heard anyone accuse Swinton of selling her art-cinema birthright for a mess of Tinseltown pottage - perhaps because of the quality of her US work, perhaps because people think of her operating there as a foreign body in the studio soup. In any case, she insists, "I've never been in something that didn't feel like an experimental film, even if two hundred thousand million dollars was spent on it." I wonder whether she now has people around her, agents or studio people, who beg her not to make Bela Tarr films as it'll ruin the new Tilda brand. Absolutely not, she says: "The people who work with me seem to get it and the people who don't get it don't come near." But her intransigence used to drive people crazy; she remembers a casting agent lamenting, "When, oh when, is Tilda Swinton going to do something she doesn't want to do for a change?"
Her change of direction may be partly to do with being a mother to 11-year-old twins, Xavier and Honor. "I woke up in every way when I had children. I just stopped arseing around. I can say [its]pretttttty[its] well," she slurs, knowingly, " I've not had one moment to waste since giving birth. Not one moment.
"Having twins will do that to you. If anything, it's widened my view on pretty much anything, and cinema particularly. Any tendency in me to be judgmental or elitist evaporated instantly. My children in their tenth year were exposed to both Bela Tarr and Pixar, and they found the Pixar film more boring." Was it WALL•E, by any chance? I ask. She leans forward, fascinated by this enigma. "What is it about children and WALL•E? They don't like it. It's too conceptual. It is a great, [its]great[its] film."
Swinton is famously a scion of a long-established Scottish family that includes Sir Walter Scott and the Sitwells somewhere among its branches, her father Major-General Sir John Swinton a former head of the Queen's Household Guards. She was also a Communist Party member, and stayed on when it became the Democratic Left but, she admits, "When I had my babies and left London, all sorts of subscriptions lapsed." She studied at New Hall, Cambridge, originally intending to be a writer, although she stopped writing as soon as she arrived and found herself acting instead. After graduating, she had an unhappy spell on the professional stage, including the RSC. She has had her moments in theatre, including an acclaimed single-hander performance in Manfred Karge's play Man To Man, which she says ruined the theatre for her, as nothing afterwards could match the experience.
It was when she met Derek Jarman, in the mid-80s, that Swinton realised that film was her thing. She was "high and dry", she remembers, confused about what she was supposed to be doing: Jarman "just allowed me to come and work it out in his soup kitchen - and work it out through silent cinema, through Super-8 autobiographical meanderings. You can't call it acting, because it isn't, you can barely call it performance, it's just getting used to being filmed and to the possibility of just doing nothing." Jarman cast her in in his 1986 Caravaggio, and Swinton became a fixture in the director's ensemble and social circle, his muse and the best-known torch-bearer for his values. Swinton's impassioned open letter to her late friend, attacking the stagnation she sees as afflicting British cinema today, was the basis of Isaac Julien's documentary tribute Derek, earlier this year.
As for "the possibility of just doing nothing", Swinton explored it to the hilt in the 1995 Serpentine Gallery installation/performance piece The Maybe, a collaboration with artist Cornelia Parker. An oblique but crowd-pulling piece, seen by some three thousand people a day, it featured Swinton lying eyes closed and largely motionless in a glass box for a week. What was going through her head all that time? " I can only tell you that when I've decided never to do it again. I've never talked about the experience, because part of the way it works is no-one knows the answer to that question. [its]No-one knows the secret of the black magic box[its]," she says, mock-portentous. "But I do intend to do it again. I'd like to do it as a very old lady and actually expire - see if we can arrange that."
Swinton turned a corner this year in terms of fame, as a result of her Oscar for Michael Clayton. She made her talk show debut on Letterman, and started finding her photo in newspapers she hadn't done interviews for. "People now wave at me in airports, and I'm pretty sure none of them have seen [Jarman's] The Last of England."
That's not the only aspect of her new celebrity. Earlier this year, Swinton caused a stir in the transatlantic press after appearing in public with her boyfriend Sandro Kopp, a 30-year-old German artist, whom she met on the set of The Lion, The Witch and the Wardrobe. This might not have been considered news if Swinton had not been known to be the long-standing partner of Scottish painter and playwright John Byrne, the father of her twins. The gist of Swinton's domestic arrangements - or "Bizarre Double Life", as one headline put it - was that, as she explained at the time, she and Byrne were still living together, but both had new partners, and that it was an amicable state of affairs with which everyone was comfortable.
Dealing with this sudden burst of press scrutiny - Swinton says, a touch wearily - was "like that ritual that Aboriginal Austalians do, of standing in the desert and letting wasps and bees fly over them and go in all the orifices and you just have to stand really still and let them do their stuff and then fly on.
"A friend of mine told me there had been a Radio 2 phone-in about us and our scandalous existence, and every single person rang in and said, 'What's the problem?' They couldn't get anyone to ring in and say anything different."
In fact, while Googling her, I found Swinton's name on several 'polyamory' websites, hailed as an inspiring example for the multi-partner lifestyle. Swinton takes this information with wryly exaggerated scepticism. "[its]Rrrrright[its].... Well, that's good. I'm sure there are red-headed websites that are claiming me, and people above a certain height. It's all fine," she sighs, cheerfully, "I'm friend not foe. One man's polyamory - is that the word? - is another man's being really, really good friends with the co-parent of one's children while we're both in other relationships. I don't think that's so strange. But maybe it is - and that would be really sad."
Meanwhile, Swinton caused an entirely different stir in her home town of Nairn, on the Moray Firth, where she lives with John Byrne and their children. This autumn, she and critic Mark Cousins got together to create a film festival there, the somewhat preciously named Ballerina Ballroom Cinema of Dreams. Very much a front-parlour showcase for favourite films, the festival invited people to turn up in pyjamas or bring their own home-baked cakes. The whole thing sounds utopian, loopy and rather precious, and I'm kicking myself that I missed it.
Her favourite festival moment, Swinton says, involved a 75-year-old woman who arrived in pyjamas with a teddy bear to see Margaret Rutherford in Murder Most Foul. "Her friend told her" - she slips into a genteel Highland accent, "'Oh, Enid, now everyone will know you weren't at church,' and she said, 'Well, this is better than church.' We had a song before every screening and that morning it was 'Morning Has Broken'. I also got them singing Marilyn Manson." Next spring, Swinton plans to take the festival to Beijing: she's looking forward to seeing Mandarin subtitles on Powell and Pressburger's Scottish classic I Know Where I'm Going.
Swinton once characterised her ideal of cinema as a 'Church for the Aliens', and she is without doubt today's most extra-terrestrial celebrant at that particular shrine. Perhaps she has never been quite so alien as in the 1996 music video she appeared in for dance act The Orb: wearing a blue rubber helmet and a Keaton-esque expression of blank bemusement, she paces slowly around a London that whizzes in speeded-up motion around her. It's a wonderfully concise visual metaphor for the way that Swinton has always walked out of step with - almost in a parallel dimension to - cinema as most of us know it. The Maybe aside, this video may be Swinton's consummate appearance as [its]object[its] rather than performer. "I think of myself most accurately," she says, "as an artist's model, and that's really what I am. Beyond that, I'm a piece of production design. I'm not interested in acquiring acting skills. What good would they do me?"
Julia is released on Dec 5; The Man From London is released on Dec 12.