Anybody who has political ambition has an Achilles heel.

What would I like? Some very silly comedy where I don't have to think about anything, but it could be a lot of fun. And if it's not that, then I'll want to be involved in something where it's like, you're really dredged up to the neck in emotion, where it's as exciting as the premise of Battlestar.

I did worry about being in a science-fiction show. The bits that I was reading, I felt were funny, and I felt the man was childish, so I really did ask initially, "Is this for kids?" And the thing that came back immediately was like, "Hey, take a look at this whole thing again. This is definitely not for children. How can you think that?"

I've been acting for years and years, at prep school - school plays, that kind of thing. That was always very high on my agenda. I went to study English for two reasons. Principally because when I was in university, studying drama wasn't considered an option. You couldn't get a degree course for it. And so many plays and things that I was interested in landed themselves in a broader spectrum of literature.

Film and television as a medium has only very recently begun to be taught at the great drama schools in the UK. When I was at drama school in the UK, I was there for two and a half years, and we did one week of television and film. It's right before you leave. It's like, "We've taught you Anton Chekhov and William Shakespeare, you are likely to be in a washing-up soap-liquid commercial."

Rather than, as an actor, I want the audience to like me, I'm going to smile beautifully and I've got everybody's sympathy - what about showing the moments when somebody is unbelievably petty? Or really selfish? The faults, the little things, those are the things that interested me about playing the character.

From university, I tried to get into the profession almost immediately, and just got kind of kicked back in London, by lots of people saying, "Well, you know, we'll need to see you in something. And the easiest way for you to get seen in something is drama school. That is the best way to get an agent."