Tilda Swinton plays a vampire in Jim Jarmusch's Only Lovers Left Alive

There's always been something otherworldly about Tilda Swinton, so the role of a 3,000-year-old vampire called Eve in Jim Jarmusch's Only Lovers Left Alive is one that she looks to have been born to play. That said, she is a consummate shape shifter.

Whether the character she is portraying is a mother at war with her son, as in We Need to Talk About Kevin, or a C.S. Lewis fairy tale villain in The Chronicles of Narnia film series, the androgynously dressed and coiffured actress brings conviction to a performance.

She sinks into her roles, sometimes - in the case of her aged dowager in Wes Anderson's The Grand Budapest Hotel or the outrageous Minister Mason in Bong Joon-ho's Snowpiercer - disappearing completely.

When we meet at the Cannes Film Festival, Swinton tells me that she tries to seek out opportunities to "give something authentic". Some parts make this easier than others. She recalls that when she played a pregnant mother in Tim Roth's 1999 incest drama, The War Zone, she was actually pregnant herself, "and in no position to contribute anything to any film, frankly. I was about to give birth so it was the only film that I could contribute anything to, because what I was being required to contribute was the authentic thing."

Her casting as the evergreen Eve is perfect, because time appears to have really stood still for Swinton. At 53, her translucent skin and angular Bowie-esque physiognomy have changed little since our first encounter, 13 years ago. In fact, so kind have the years been to Swinton that I start to wonder whether she isn't a real-life Dorian Gray.

"I do feel like I have lived for several centuries," she says. "Even if it's short, life's long. So Eve wasn't a stretch for me. But at the same time, of course, these immortals know they're not going to die; I'm clear that I am. But then there's an element in which all artists never do. So that felt familiar, too."