There are some interviews that are difficult to sit through - not because the movie star is arrogant or boring but because, in a group interview, the behaviour of the other journalists can make you ever so slightly nauseous.
And so it was with Keira Knightley.
With the bearing of a ballerina, crisp diction and startling beauty, she had a powerful effect on the male journalists in the room. Moments before she walked in, they seemed tough, jaded - so over this whole movie promotion thing - but suddenly they were transformed into schoolgirls.
They giggled at her asides, they blushed like maiden aunts when she said the words "f---" and "t*ts", they didn't dare ask the questions that may alarm her (i.e. "Keira, do you have an eating disorder?")
Instead, one older gent asked her how many pairs of shoes she had, while another stared agog and asked her about her favourite football team, while another praised her for her charity work (she auctioned off a dress she wore to the Oscars, proceeds going to Oxfam).
It was a relief then, when she didn't engage in the sycophantic role-playing that is part of film promotion these days - the pretence that every question is insightful, that the journalist opposite really is the most charming, intelligent person on Earth, and that quite possibly we could all be best friends if it wasn't for such demanding filming schedules.
Instead Keira Knightley was haughty, sharp, and at 22, is not afraid of verbally kicking in the balls of journalists twice her age.
When asked by a leering journalist about "you know - getting your gear off, love" (Knightley first appeared naked aged 15 in a movie called Hole, and more recently was starkers on the cover of Vanity Fair with acting colleague Scarlett Johansson) - she was more than his match.
Journalist: "In Silk I hear you are appearing half-naked at some point ... is that right?"
Knightley: "What?"
"Err, sorry, in Silk ..."
"Silk!"
"I read -"
Knightley interjects in that posh, quite intimidating voice: "Have you read the book?"
Journalist:"Well I just read that you might ..."
(Other journalists in the room are squirming in a "pull out now, mate" way.)
Knightley - sharper and slowly: "Have you read the book?"
Journalist: "No."
Knightley: "Well, in the book, there are several sex scenes."
Journalist:"OK."
Knightley: "So it's an adaptation that's very true to the book."
Pause.
Knightley: "I mean Jesus Christ, it's not like I haven't taken my clothes off before!"
Journalist:"I was just going to ask if you are comfortable about it - "
Knightley: "People will start paying me to keep my clothes on. No, I don't have a problem with it. I've never had a problem with it. I don't believe in censorship. So I never think I have done anything wrong. I suppose I am very European in my feelings towards my body."
So there!
In London promoting the third in the franchise of Pirates of the Caribbean movies, it's clear the 22-year-old actor has a remarkably strong sense of self.
In person, she has chocolate brown shoulder-length hair and skin the colour of milk. She looks lean and healthy - less emaciated actor, more sleek greyhound who has realised her body is a tool of the trade and has disciplined it accordingly. In person she is not as orange as on the promotional posters for Pirates - in which she looks as though she has spent an excessive amount of time being spray-tanned.
Knightley is currently riding high as the Brit Pack's queen of Hollywood. Not only has she gained a legion of fans in the three Pirates movies, but she has also interspersed them with art house, riskier ventures and critically acclaimed classics such as Pride and Prejudice (scoring herself an Oscar nomination).
While contemporaries such as Sienna Miller are still floundering while looking for the right role, Knightley is already a veteran of a wide range of television and film parts.
Born in London in 1985 to an acting family (her father is jobbing British TV actor Will Knightley), Knightley started as a child, appearing in shows such as The Bill, but it wasn't until the 2002 indie hit Bend It Like Beckham that people started taking notice.
She was an interesting choice for the role - almost too feminine, willowy and gorgeous to be believable as the tomboy soccer player. She was more aptly cast in Love Actually - as the English rose who is the focus of a painful unrequited love. Many of her memorable scenes in that film were video footage shot of her looking lovely, and replayed: Knightley wearing a pretty dress, Knightley dancing, Knightley waving goodbye, while the man who desired her sat passive and yearning before all that unattainable beauty.
So it seems in real life that we can't get enough banal shots of this lovely girl. The British tabloids are full of pictures of her doing mundane things - just being Knightley, going for a walk, buying a big latte, or lying in the park with her boyfriend Rupert Friend. It is as if we are the unrequited lover in Love Actually, transfixed by her image.
Put that to Knightley - ask her how she feels about the public's appetite for seeing all those photos of her - and the steel in the girl comes out again.
She fixes me with a fairly scary stare when I ask if she "minds the paparazzi" and says: "Legally I don't have a choice about it; I have to deal with it. I...think...that...it...is...sick. Very well-chosen word. I dunno. I think it's sick."
She continues with a few more well-chosen words.
"I think the pressures put on women of a young age of a very vulnerable group are huge. But indeed it's not about what people say or what the pictures look like. It's about a young woman being followed around by five men who could be anyone and you have no way of telling who they are - if they're legitimate photographers or if they're r*pists. It's terrifying - it's totally terrifying and I don't think that's right - I think that that's very wrong. I don't necessarily have a good level of anonymity in London. It's pretty much the same everywhere. I haven't really found it better or worse in any other city."
It's the Pirates series more than any other films that have extended the reach of her global recognition.
Their appeal is basic: they are good old-fashioned adventure films that appeal to both kids and adults alike, and each one has been more lavish than the last.
But they also sound like a nightmare to shoot. Some of it was to a blue screen, which Knightley found difficult ("it is slightly ridiculous when you suddenly go, 'Ohhh, I'm meant to be really frightened of him' and it's Bill Nighy in his skinny grey suit").
Shooting on location also sounded tough: "The last six weeks were in torrential rain with the stage on a rake so we were running uphill and we had to wear wetsuits and we had to do intense fight scenes in a wetsuit running uphill. I was training pretty non-stop on a cross-trainer every night just trying to get my cardiovascular up 'cos it was sh*t but that was pretty strenuous."
Coming up is Silk (beware, there is Knightley nudity!), an adaptation of Ian McEwan's Atonement and a part in the Dylan Thomas biopic, The Best Time of Our Lives, where she battles Sienna Miller for the love of the drunken Welshman.
Knightley is excited about working with that film's screenwriter, her mum, Sharman Macdonald. "The pressure was really on her to deliver a really great script and she totally, totally lived up to that - it's an absolutely beautiful work."
She recently had a five-month break from filming where she "needed to have a bit of a breather and live in a flat that I actually bought three years ago but never lived in."
She says, "I did absolutely nothing, I walked around, I cooked a lot, I had friends over to my flat and we drank very good wine."
Cooking a roast chicken is a favourite pastime, as is creating her own stock and freezing it for risottos and soups.
A publicist comes in and says our group interview slot is over and Knightley, in the manner of the Julia Roberts' character in Notting Hill, will be moving into another suite in this Knightsbridge hotel to go through the whole thing again.
After the interview I wandered around for a bit. The publicity machine for Pirates has taken up a whole floor of this hotel. There are make-up artists running around and cables taped to the ground, satellite feeds to Asia, someone shouting, "Orlando? Yeah, Orlando's almost done!"
I thought somewhere in the next room someone will ask her about her weight and, in another interview, more journalists will either attack or fawn, and it will be hour after exhausting hour of unreality. Maybe that's where she gets her steeliness from -it's honed in these tedious hours of strangers asking you about everything from your body, to the food you put into it, to your sexual relationships, to your parents.
Then when she gets home to central London, five or so men will be at the front of her house and they'll photograph her living the life she has just spent the day discussing with strangers.
Pushing the button in the lift and escaping to the relative lack of artifice that is Sloane Square, I preferred to think of her cooking for her friends in her flat, freezing chicken stock, getting drunk on good red wine and having a laugh at how weird life is.
I think that off duty, that's the sort of girl she would probably be.
No Keira pictures at the premieres? 
