We had an ancient Russian acting coach at my drama school who said the worst offense you could commit was to let your subtext show. That is the point of acting, is to be saying one thing and not be allowed by society or your predicament to show what you're really feeling. In a way, I think that's why the therapy generation has killed script writing, because all you ever get is people going, "Hi, I'm feeling really angry right now."

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.

My parents have always been cool. They even became surrogates to friends of mine who didn't have such supportive parents.

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."

If the role is right and it's another situation of having a benevolent genius at the head of it, someone who likes actors, and will protect the actors from the ravages of reality-TV drama. It's a brutal world, and you need to have a strong creative team who can stand up to the network.

The excruciating moments of drama are when people are allowed to show or say what they feel.

I wanted to play a TV detective because it's a rite of passage; I wanted to experience every area of acting. I haven't done comedy or as much Shakespeare as I had intended.