Madonna has been up partying for most of the night. "I've had about four hours' sleep," she says. "And I feel like I've been run over by a truck."
She doesn't look particularly tired, although it's rather hard to tell because that famous face is a mask of make-up - she's come straight from TV interviews - beneath a curtain of perfectly sculpted cornfield-yellow hair. And she certainly doesn't seem nervous either, although she says she is.
Where once she played sell-out stadiums around the world, right now she's on a very different kind of tour, taking in Venice, Toronto, London and New York, where she's promoting her debut feature, W.E. (opening in cinemas here on Friday 20 January), a fictionalised story based around the romance between King Edward VIII and American divorcee Wallis Simpson.
She knows, of course, that the critics are out there waiting, pencils sharpened, eager to pass judgement on Madonna the film director. "Of course I'm nervous," she says. "I think being nervous means you care about something and want the outcome to be good. I come to the art of film-making with great humility; I respect it immensely as an art form and I know I have a lot to learn.
"It would be great if people liked my movie and it's a success because that means I will be able to influence people. Let's be honest, one doesn't put all this hard work and effort into something, then say, 'I don't care if people see it or not, I don't care if people like it or not...' I hope it finds an audience."
She is, then, stepping outside her comfort zone. But, then again, reinvention has been her speciality. She was born Madonna Louise Ciccone in Bay City, Michigan, 53 years ago, but by the time her debut album was released in 1982 she was simply known by its title, her first name.
And that's the way it's been ever since as one single after another - Material Girl, Like a Virgin, Papa Don't Preach, Like a Prayer, Express Yourself, Take a Bow, Ray of Light, What It Feels Like for a Girl, Music, American Pie and many more - and the albums they were drawn from dominated the charts worldwide.
Along the way, she has become a popular music icon to rival Michael Jackson, the Beatles and the Rolling Stones, selling more than 300 million CDs, and has rarely been out of the headlines thanks to a tempestuous relationship, and marriage, to actor Sean Penn and a second marriage to British film director Guy Ritchie, which lasted eight years.
She has two biological children, Lourdes, 15 (from her relationship with Carlos Leon, a personal fitness trainer), and Rocco, 11 (with Ritchie), as well as an adopted son, six-year-old David, and daughter, five-year-old Mercy, both born in Malawi.
She's acted, with mixed results, in numerous films, including Desperately Seeking Susan, Dick Tracy and A League of Their Own (all good), Evita (not so good) and Swept Away, directed by husband number two and regarded as a turkey. She's written a series of bestselling children's books and posed for some very risque photographs for a coffee table tome called Sex, which was definitely not for children.
Raised a Roman Catholic, she is now a follower of the Kabbalah faith, an offshoot of the Jewish religion. She's also opened fitness centres (Hard Candy gyms) in Mexico and Russia, launched clothing lines (Material Girl, of course) and raised funds for an acadamy in Malawi. She's not easy to pin down and clearly doesn't see herself hemmed in by boundaries. So why not try her hand at directing a movie, too?
"I've been on a few film sets in my day and I've been married to a few directors and I've been friends with a lot of directors. I've picked up a few tips and I've paid attention," she smiles. "I watched closely what both Sean and Guy did. With Sean, I saw the importance of rehearsal and preparing and doing as much work as you can ahead of being on set. Guy is a much more visual director and he takes a lot of chances and risks when it comes to camera moves and things like that. And I learned a lot from him in that respect."
She first became interested - some might say obsessed - with the Edward and Mrs Simpson story when she moved to England after marrying Ritchie in 2000. "I really didn't have any friends, I didn't know anybody, and I found myself in a strange world so I decided that I was going to educate myself and find out about the history and culture of this new world that I lived in.
"So I started studying English history - I started reading about the monarchy, starting with Henry VIII and then I worked all the way up to the Windsor family. I'd heard about Edward VIII abdicating when I was in school. I knew that he had given up the throne for this American woman from Baltimore and that was it.
"I researched it more and I was kind of transfixed by the idea that a man would give up such a powerful position for love. I felt that there was something kind of Shakespearean about it.
"And so I started to investigate further - I started reading books about Wallis Simpson and I found a lot of them to be really negative and one-dimensional. She was accused of all sorts of things, from being a Nazi to being a witch or a sorceress with magic powers that put a spell on somebody.
"I saw a pattern that we have in society - that when women have some kind of power, and we don't understand them, we have to diminish them by turning them into heretics. When they are perceived to have too much power, we say 'oh, that's because she's a sorceress...' "And, by the way, I don't believe they were Nazis. In fact, I did as much research on that as possible - I was looking for that empirical proof and I couldn't find it."
There are, perhaps, elements of Wallis Simpson's story that she can identify with, too. Mrs Simpson's affair with the King scandalised a nation and from then on she lived her life in a blaze of headlines, often vilified. Madonna, too, knows what it's like to have your every move scrutinised and discussed and to live inside the goldfish bowl of fame.
"I think I had an insight into her character that possibly other directors wouldn't have because I know what it's like to be reduced to a soundbite," she says. And she believes that we shouldn't assume we know someone - and she's obviously talking about herself here - simply because we see unguarded snaps of them in newspapers and magazines.
"We live in a society that is obsessed with celebrities and it's pretty easy to get famous pretty quickly now. I think people mistake seeing a photograph of somebody playing on the swings with their children as an insight; they assume that it's some kind of intimacy. But you don't really get to know a person that way because their lives have been intruded upon - it's an illusion."
She arrives for our interview, the morning after the Venice premiere of W.E. (Wallis and Edward) and associated late night, flanked by a posse of burly, dark-suited Italian bodyguards all wearing regulation sunglasses. In among all those heavies, she looks tiny and up close she looks smaller than you'd expect - she's 5ft 4in - but then fame magnifies and exaggerates everything, especially Madonna.
Her slight frame is encased in a black, kneelength, lacy Dolce & Gabbana dress and she wears a silver Cartier bracelet with crosses around her wrist - a copy of the one that Edward gave to his bride. "The real bracelet has seven crosses on it and this has four," she says. "And Cartier gave it to me as a present at the end of the shoot."
In W.E. the build-up to the abdication is told in tandem with a more contemporary story, set in the 1990s, where a young American woman, Wally (Abbie Cornish), is trapped in a loveless, abusive marriage. She is obsessed with Edward and Mrs Simpson (her namesake) and begins to research their relationship in the run-up to a New York auction of artefacts owned by the couple.
"Wally wants to understand the nature of Edward and Mrs Simpson's love story. When she says 'I wonder what it was like to have been loved that much?' I think I probably said that to myself. "Men want power and they will kill to have it. If you look back in history, how many wars have been waged to win the throne? And here's a man who walked away from that for love. And so for a romantic like me, I would say 'Wow, to be loved like that!' And Wally feels the same way - she wants to be loved like that."
In flashback, we see how Wallis Simpson (Andrea Riseborough) herself suffered violence at the hands of her first husband and, arriving in London, is drawn into the glamorous social scene with Edward (James D'Arcy) at the centre.
The film has already had mixed reviews from the festivals in Venice and Toronto and some have been harsh. But you can't help but wonder whether, if it had been made by an unknown, first-time director, the reviews would have been entirely different and, quite possibly, more favourable. But the flip side is that W.E. wouldn't generate the kind of publicity blitz it has if Madonna wasn't the director. And while this certainly isn't a rival to The King's Speech, which is set in the same period and involves many of the same royals, it isn't as bad as some of those early reviews claim.
It's beautifully filmed and has been nominated for two Golden Globes, for best original score, by Abel Korzeniowski, and best original song, Masterpiece, co-written by Madonna. "I'm well aware that everything I say and do is judged with a different measuring stick to most other people," she says. "I'm under the magnifying glass in a way that other people aren't, but I can also use that. I can influence people."
And at the heart of her film is the story that has transfixed generations - a man who gave up the throne for love. "I've been asked many times if I would give up everything for love," she says. "And I think it's important to understand that with love, and in all relationships, you have to give up something.
"What Edward gave up was huge, monumental, but I also don't think that he realised that when he abdicated he was never going to be allowed to come back into the country, that he was never going to be able to serve his country in any way, shape or form. But we live in a different time now, so we have the luxury and the ability to be able to do several things, to have careers and families, and to love. Although it is a juggling act and you have to make compromises."
Her latest partner, dancer Brahim Zaibat, is just 24 and that has produced another flurry of stories. But while she's not about to reveal if she plans to make him husband number three, she clearly believes that love can flourish whatever the barriers - whether that be age difference or, in the case of Wallis and Edward, social standing.
"There is no such thing as perfect love but on the other hand I do believe in romance. I do believe in true love and I do believe it is possible for everyone if you are willing to make compromises." She doesn't dwell on the past or, indeed, the various incarnations that she's projected on to the world. Will the real Madonna please stand up?
Probably not, because keeping us all guessing has been a crucial part of her success. "I don't think much about me in the past to tell you the truth," she says. "Because I'm too busy looking forward." And doubtless, with a new single and album due in March, the highly coveted live appearance during the Superbowl in February and tentative plans to direct another film, there will be another Madonna with us soon.