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.

I had the best teacher in the business. Kevin Costner was my teacher. I was acting opposite him and he was directing me. The way he directed me, for which I am eternally grateful, is he would watch the scene back on the monitor, which is sort of considered unfashionable - you're not meant to watch yourself. But he was like, "Come around. Watch this. See there, you're doing a great reaction, but you're doing it out of frame." That was exactly what I needed. I learned how to act on film from him.

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 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.

Ewan McGregor is a very genial and entertaining man, and Pierce Brosnan is possibly the nicest man in the world. Actually, it was quite a genial set The Ghost Writer, but the weather and the colors and the actual surroundings were oppressive. But it was a created atmosphere. What was so striking is that Roman Polanski had his crew from The Pianist, and we were shooting in Berlin, so there were German and Polish and French people, and I was just sort of enjoying being in this mix of people, all kind of rubbing along together. That felt good.

I don't tend to spend the whole day in the personality of the person I'm playing.

The way I miss my daughter Esme is to worry about her. It is not a pleasurable longing. It contorts my body and scrambles my brain, makes me stop breathing, clench my jaw and my fists, it makes me frown, and makes me blind and deaf, in fact entirely without sensory perception.