This might be taking her promotional duties too far. Padding into the room without shoes, her legs clad in fishnet stockings, Nicole Kidman arrives in a funereal black skirt and embroidered jacket designed by her "friend", L'Wren Scott. She looks like she's stepped straight off the set of her new film, Stoker, a gothic blend of murder and intrigue from Park Chan-wook, the South Korean director of Oldboy. "I'm dressed in the costume," she jokes. "I kind of noticed that today."
At least she hasn't come in the outfit she wore in her previous film, Lee Daniels' sweaty erotic thriller The Paperboy, in which she played a Southern sex-kitten who totters around in high heels and dangerously short miniskirts. No, as ever, Kidman is the epitome of old-school Hollywood glamour. Later in the evening she'll grace the Stoker premiere in another L'Wren Scott outfit - this time a figure-hugging mid-length blue dress that, just hours earlier, was unveiled at Scott's first-ever London Fashion Week show.
Right now, Kidman's fighting jet-lag, having arrived from Tennessee where she lives with husband Keith Urban and their two young daughters.
"I just got in yesterday and I made the mistake of lying down at lunchtime - not smart," she says. "I was out of it. But here I am!"
Polished she may look but the willowy, pale-skinned Kidman doesn't spit out the usual platitudes. At this year's Oscars, while presenting an award, she went off autocue to apologise to director David O. Russell for accidentally talking over his applause.
For some years now, certainly since her 11-year marriage to superstar Tom Cruise ended in 2001, Kidman has been let off the leash, creatively speaking. From winning an Oscar for her take on Virginia Woolf in The Hours to arduous, emotional odysseys in films such as Birth, Rabbit Hole and Dogville, Kidman has stretched herself to breaking point, far more than in the years when she was married to Cruise, starring with him in cookie-cutter films such as Far and Away and Days of Thunder.
So is she conscious that her priorities have changed? "I'm just interested in things that are not so mainstream," she says. "I like things that don't conform. I used to try to conform more and fit into an idea of what you're meant to be in terms of a film actress, but now I don't bother. And I think my spirit probably tends to be a 'buck the system' spirit anyway. So I've always had that.
"I dig my heels in every now and then, and think: 'I'm not going to do what's expected or what people think is the right thing'. So I have a little bit of that in my personality."
Certainly, both Stoker and The Paperboy fit that mould. A disturbed family portrait, coming-of-age fairy tale and gothic horror all in one, Stoker casts her as Evelyn Stoker, a widowed mother (to Mia Wasikowska's insular India) whose grief is disturbed when her late husband's mysterious younger brother (Matthew Goode) arrives unexpectedly to stir up dormant emotions. Violent, sexual, creepy but also artful and assured, Kidman notes that working with "Director Park", as she fondly calls him, "was like being one of his instruments". Written by Wentworth Miller (the Prison Break star who co-starred with Kidman in 2003's Philip Roth adaptation, The Human Stain), Kidman admits she was drawn to playing the "instability" of Evelyn.
"This has got some Tennessee Williams overtones," she notes, "even though Park was like, 'I so don't want this to be like a Tennessee Williams character!' He didn't want it set in the South, which is why we don't have Southern accents. He wanted it almost timeless."
The Paperboy, on the other hand, was very much of its time. Set in 1969, and adapted from the novel by Pete Dexter, Kidman played Charlotte Bless, a disturbed woman with a penchant for men behind bars, notably John Cusack's death-row killer.
Perhaps her most unhinged character since her murderous weather-girl in 1995's To Die For, it's not hard to see the attraction for Kidman, who won a Golden Globe nomination for the role.
Littered with over-the-top sexual scenes, it made her turn with Cruise in Stanley Kubrick's sexual odyssey Eyes Wide Shut seem quaint by comparison. One scene saw an abrasive sexual encounter on top of a washing machine; another, what Daniels calls the "telepathic sex scene", had Cusack's sweaty inmate bring both him and Kidman to orgasm just by leering at her.
"I just never get asked to do roles like that," says Kidman. "[It's] a lot rawer than I've been before and obviously the sexuality of it was frightening, but at the same time it's my job as an actor to commit to the role and not, through my own inhibitions, run away."
She didn't even balk at the scene where Charlotte urinates on Zac Efron's lusty character, Jack, after he gets covered in jellyfish stings. "I just went for it and didn't over-think it," she says.
It takes a lot to psych herself up to play these challenging women, though. "I'm always worried, about every role. I think I've got the reputation of always trying to pull out of stuff. Part of it is fear and part of it is it seems overwhelming, and I can suddenly come up with 10 other people who would be better at it than me. My mind plays tricks on me, so I have to just jump in - once I'm there, I'm fine. Then I love it. It's just getting there.
It's like this weird push-pull. And now I have an awareness of it I can [deal with it]. When I was younger it was more like a roller-coaster."
You might say that her entire life has been like that. Born in Hawaii but raised in Sydney, her father worked as a biochemist and clinical psychologist, and her mother as a nurse educator.
Kidman made her movie debut, aged 16, in BMX Bandits. She stopped acting for a year while her mother successfully fought breast cancer, but Kidman's rise to stardom seemed inevitable after the 1989 thriller Dead Calm and two television mini-series, Bangkok Hilton and Vietnam, propelled her into the public eye.
Then came the blur of the Cruise years followed by artistic triumph in the wake of their divorce. Yet Kidman's not afraid to open up about how vulnerable she felt when she won an Academy Award in 2003 for The Hours.
"It was a mix of popping a champagne bottle but at the same time feeling incredibly lonely. Just because I didn't have what I have now. And those situations when there's an enormous amount of professional success, that can only magnify sometimes the things you don't have in your real life."
What she didn't have, at that point, was domestic bliss. Splitting from Cruise shortly before she went to Cannes with Baz Luhrmann's musical Moulin Rouge!, Kidman admits it was the start of a "very strange" period in her career, which culminated with her Oscar win two years later.
"It was the collision of professional success and personal failure," she says. "I desperately wanted to have a baby and I wanted to have a real life, I wanted a full life. I didn't even have a home then, I was renting and just moving around, very gypsy-esque."
She and Cruise had two adopted children Isabella (20) and Connor (18), but it wasn't enough. "That's when I went, 'I want to have that person. However many years I get given, I want somebody who's going to share all that with me."' Fortunately for Kidman, she met country singer Keith Urban who suggested they settle in Nashville.
"I had no place to live. When my husband said, 'I actually live in Tennessee', I was like, 'Definitely not a deal-breaker!"'
Having given birth, aged 41, to Sunday Rose (now 4), Kidman and Urban then welcomed their second daughter, Faith Margaret, into the family two years later, born via a surrogate mother.
"Being a mother and wanting to be a present mother," Kidman says, means she has to manage her workload carefully. Both Stoker and The Paperboy were three-and-a-half weeks apiece, as was her time on next movie The Railway Man, an account of World War II survivor Eric Lomax, in which she co-stars with Colin Firth.
Kidman went from that to Grace of Monaco, in which she'll play the alluring movie star Grace Kelly in a story that depicts her intervention between France and Monaco in 1962, when the two states were in dispute over tax laws.
"I didn't try to pull out of that one," she laughs. "I just fell for Olivier [Dahan, director], who is this magnetic personality. And I loved living in France and giving my children a bit of that lifestyle. We had some gorgeous places where we were. That was actually a big workload."
Kelly, of course, became Princess Grace after she married, in 1956, Monaco's Prince Rainier III (played by Tim Roth).
Already the film has caused a stir, after their children issued a statement lamenting the "pointlessly glamorised" depiction of their mother. Whatever the truth, "I know quite a bit about her now," says Kidman, who speaks of the "tenderness" she feels towards Kelly.
A star who left Hollywood behind for love? It almost sounds like Kidman's own story.
Stoker is in cinemas on August 15.