It's the day before the world premiere of Diana in London and the movie's star, Naomi Watts , though looking sleek in a black Victoria Beckham dress, is clearly a nervous woman.
Her promotional schedule in the days prior to the premiere has been cut back and she's joined by the calming figure of director Oliver Hirschbiegel for every interview.
The pair admit to being "concerned" what the royal family will think of the biopic charting the Princess of Wales' romance with heart surgeon Hasnat Khan. But, the director shrugs, "You try not to p--- somebody off without reason".
It's not the royals the team behind the movie should have been worrying about. When the reviews from British critics break after the premiere, they are vicious. "A special class of awful," went one. "Fabulously awful," went the next. Princess Diana, said another, "has died another awful death".
Hirschbiegel has since pointed to a more positive reaction in other European countries; concluding that the British are just too close to the subject: "Diana is a trauma they haven't come to terms with."
Watts was 28 when Diana died. Having moved from England to Australia at 14, she wasn't bombarded with stories about the Princess as she might have been had she stayed. Still, she remembers clearly where she was when news of that crash in a Paris tunnel broke.
"I do remember the news ... and being quite traumatised by it. I was in Canada, probably filming a bad TV movie. And I was with, funnily enough, Rob Lowe and his wife.
"We were at dinner when we were told Dodi was dead. In the time that we left the restaurant and got back to the hotel, the bad news was revealed."
Watts has played real-life characters before - she was Oscar-nominated earlier this year for her portrayal of a mother caught in the Boxing Day tsunami in The Impossible.
"Of course with Diana I had the responsibility of telling the story in a truthful and sensitive way, but with the additional pressure of looking as close to her as possible and getting the voice right and all those things.
"Playing the most famous woman of our time is incredibly high-pressured because everyone feels they know her, so therefore she belongs to them. How can you take possession of a character that everybody knows so much about? That's a daunting thing."
While initially reluctant, once on board the film, Watts threw herself into the role.
"I saturated myself in all of the information available: I read every book, every old news article, watched every piece of footage I could find."
A couple of breaks in the shooting schedule - one before filming sequences in Mozambique, another due to Naveen Andrews (who plays Khan) being injured - caused the production to lag a little.
"The stopping and starting made it difficult. So by the time we got to the finish line, I was ready to finish," Watts laughs. "Being obsessed with that character, it was exhausting."
Hirschbiegel calls Princess Diana "the most complex character I've had to tackle to date". This from a man whose most famous film, Downfall, was about Hitler.
"No really, this woman does not cease to amaze me," he insists. "And there's way more, even, that could be shown, but that would be too much for the two hours that we have."
Watts' admiration for certain aspects of Diana's personality grew the more she learnt.
"I discovered things like her great wit. It was there on the page, but the people I spoke to that knew her also endorsed that. She had a really cheeky sense of humour and liked to crack icebreaker jokes.
"I liked the rebellious streak in her. And there's no question that her compassion and empathy were huge parts of her personality. She did some groundbreaking work, starting back in the early '90s when we didn't know much about AIDS and we saw her holding somebody; that was a big thing." (Watts has worked with the UN on AIDS awareness programs.)
Asked whether she believes Diana was a brave or a tragic person, she replies, "Well, tragic ending, of course. But she was very courageous, very bold and brave. There are certain things that she did like the Bashir interview which had to have taken a lot of courage."
It was the 1995 Martin Bashir interview - in which Diana spoke of her split with Prince Charles - that became Watts' bible for nailing Diana's voice. "It was the most candidly I heard her speak, really. I would listen to that all day long."
A voice coach also had her master the British "stiff upper lip" by putting "cocktail sticks in my mouth to paralyse my face".
But getting those posh vowel sounds right wasn't overly hard for one reason: "I am British," says Watts. "People think of me as Australian and my voice is Australian now as well. But I do have an open ear having grown up in those two countries."
At 44, Watts is now largely based in New York with her partner, actor Liev Schreiber, and their two sons, Sasha and Sammy. But when it comes down to it, is she British or ... "I'm both! Don't get me in trouble!" Watts cries, anticipating the question.
Still, how does Watts describe her connection with Australia these days?
"Oh, very strong. I'm just both. I grew up here, I do feel very British. My mother still lives here, well, between here and France and Australia. She's got a good life!
"But I go back as often as I can to Australia. I try to go for Christmas. I've got my grandmother there, I've got my aunts there, I've got cousins there. And it's very important for me to have the children feel that connection.
"I never had an Australian passport and that's why, when I fill out those forms every time I enter a country, I write 'British'. But I'm working on getting an Australian passport," she laughs.
"And my heart is in both countries. That's how I can answer it."
Ultimately, Hirschbiegel reckons the Diana he has put on film is "what I would call a 'cool chick' ".
Watts captured that cool in front of moving and still cameras, recreating famous images of Diana such as her Mario Testino shoot and sitting with her legs dangling off the diving board of Dodi's boat.
"It's definitely eerie," says Watts, of seeing herself transplanted into those images.
Hirschbiegel takes that feeling and doubles it: "For me it was like watching a ghost."
However, for all the red carpets, gorgeous gowns and media attention on her own life, Watts says she can only relate to Diana's fairytale/nightmare "on a minor, minor scale".
"I've had my frustrations and my altercations with paparazzi, but nothing to that level."