Tilda Swinton is one of cinema's great chameleons, often barely recognisable from one film to the next.
And never have the changes been more extreme than in her latest work, where the roles have included a crumbling dowager countess in Wes Anderson's The Grand Budapest Hotel; a crazed fundamentalist enforcer with a thick Yorkshire accent and false teeth in Bong-joon Ho's Snowpiercer; and in this week's release, Jim Jarmusch's Only Lovers Left Alive, a 3000-year-old vampire with white-blonde locks and the body of a catwalk model.
Off-screen, Swinton is also difficult to pin down. Born of aristocratic stock and privately educated, her cut-glass English accent belies her ancient Scottish heritage on her father Sir John Swinton of Kimmerghame's side, and, more surprisingly, her Australian roots on her mother Judith Balfour Killen's.
She tells me in Cannes that the latter's death in 2012 informed the way that she came to view Only Lovers Left Alive as she was working on it. Where many will see the languid tale of vampire lovers, Adam (Tom Hiddleston) and Eve (Swinton), adrift in a world from which they feel increasingly disconnected, as a meditation on immortality, for Swinton it's asking: "How do you die? How do you bear the death of your loved ones?"
When I question her about whether she feels in any sense Australian, Swinton reveals that she has been thinking about "Australianness" a lot, recently, and admits to feeling "embarrassed" at how few times she has visited her mother's homeland.
"I was tiny when I first went. I then went to the Sydney Film Festival for about two days 20 years ago and, apart from that, I have not been. So since our mother left us (Swinton has three brothers), I have been trying to download that part of my DNA, and I will go and have a little rummage around at some point."
The actress isn't entirely to blame for her absence. Although her mother was Australian, Swinton says "she always thought of herself as a Scot, because her mother, who was a Scot, was always like: 'You are Scottish!'
"So then my mother married a Scotsman, went back to Scotland and later, from us, there was this sort of 'Hang on, you spent the first 25 years of your life in Australia . . .' So we have to go back and recoup."
It is not only her mother's death that hangs over Only Lovers Left Alive. Swinton sees vampires as a fitting metaphor for the lives of artists - particularly the outsider kind "who work in the backwaters of society and aren't committed to their work being fronted up" - who gain immortality not least through their impact on other artists.
Swinton, famously, cut her teeth in cinema collaborating with the British avant-garde filmmaker and polymath Derek Jarman (her first screen role was an artist's model in 1986's Caravaggio). At the time of his death, in 1994, they had worked together - almost exclusively - for eight years and made seven films. Through him, she learned about the "immortality of the line".
"Derek Jarman was always very clear that he was only carrying the baton that had been passed on to him by people like William Burroughs or William Blake," she says. "And this is sort of the way in which I feel about being an artist. You're part of something bigger than you. It's not necessarily being part of a movement but being part of a family. A bloodline."
Two decades after Jarman's death, Swinton is still "cleaving to the same stream". She has done some more commercially oriented projects but not because she sought them out. When she worked with New Zealand's Andrew Adamson on the Chronicles of Narnia series, it was because he'd approached her. "So it's more a question of the mountain coming to Mohammad, I suppose, than the other way round."
Working with Jarman taught Swinton that the most important thing is a shared sensibility. She's described herself as an "alien" and a "freak", and is good at recognising kindred spirits. Years before she met Jarmusch, for example, she sensed a kind of kinship with the quiffed auteur.
"When I saw Stranger than Paradise I was a student and it was the first American independent film that I saw that felt like it was America from a stranger's point of view. I've always cleaved to that and thought 'Yeah, I recognise that, you're a brother, I can hear that sound'." They've now made three films together - Broken Flowers, The Limits of Control, Only Lovers Left Alive - and "he feels like family", Swinton says.
The same is true of David Bowie. As a 12-year-old, and feeling, she has said, like "a square sort of kid in a round pond sort of childhood", Swinton carried around a copy of Aladdin Sane because the rock legend's appearance on the sleeve made him look like "the image of planetary kin, of a close imaginary cousin and companion of choice".
She eventually met him in London, and recently appeared as his wife in the video for the single The Stars (Are Out Tonight). In Cannes, she was "longing" for Bowie to see Only Lovers Left Alive, because of a line he sings in the song - "The stars they live forever". "It's kind of about the same things," she says. "Great artists being immortal."
Looking at Swinton's seemingly ageless angular features, you might wonder whether she hasn't found the key to actual physical immortality. In reality, the 53-year- old finds life just as fatiguing as the rest of us mere mortals. So what is the key to her youthfulness?
"Personally, I think one needs to reboot oneself constantly," she says. "And the two things that I find most nourishing are friendship and nature. That'll keep you going."
'You're part of something bigger than you. It's not necessarily being part of a movement but being part of a family. A bloodline.'