I'm not much of a Method actress, so even though my character in The Ghost Writer was quite dark and bad-tempered, I could only do that if I was seeming quite perky.

I think it's quite lucky that I lead this lifestyle, and in fact, my career's only gotten better as I've looked older, because it ages you, the uncertainty.

It's funny, when people want things to be very truthful and you're dealing with an inexperienced actor. I'm of the school that believes things like that have to be very carefully choreographed. You need people there to say, "It's going to happen like this."

Joss Whedon writes beautiful drama. His sensitivity and his sense of drama and scenes are pretty exceptional. There's no one else writing like him, really, in sci-fi and TV. That's not to say there are no astonishing writers on TV. I was nervous about coming to America and playing an English person who speaks very English when all the writers are American, because it's a very particular thing to imitate, and if it's badly imitated, it sounds painfully contorted and silly. And he writes very well for English people. It was Joss Whedon who persuaded me.

As I was getting into the helicopter, a slightly nervous actor said to me, "Whatever you do, don't say to the helicopter pilot, 'Show me what this baby can do.'" So I of course, got into it and said, "Show me what this baby can do." And we just had this insane helicopter ride. It's the sort of thing you only get to do on movie sets. I'm so lucky to have done it and have that chance.

I loved Rushmore. I loved the script. I mean, that is what drew me to it, just the actual piece of literature the script is. But I never thought in a million years that anyone would see it or respond to it. It was an absolute joy that it was so loved and continues to be. The same with The Sixth Sense. I thought, "No one's going to watch this. Bruce Willis hasn't got a gun. There's no shagging. Lovely story, sweet and profound about loss and death, but no one's going to watch this."

Roman Polanski actually said as much to me once. He had his head in his hands, and I said, "Roman, I've got to tell you, as an actor, seeing the director with his head in his hands... Look, I really want to do what you want me to do." And he went away and he came back, having obviously thought about what I said. And he said, "When my head is in my hands, I'm closing my eyes and trying to remember what I saw in my head, before any of the stuff."