Having gone through editing process, I can see that in actor's faces there's point where they're not managing their performance and that's, I think, the best place to be. You've done the homework, you've learned the lines, at that point you just sort of let it out.

Voldemort? That might be real.

The actor shouldn't edit themselves or be anxious. And the actors that I admire are always the ones who are inventive and their imaginative life in free-willing. It's a director's job to go, "No here, don't do that, go there."

I should say, a piece of advice that was given to me very early on by the principle of RADA (Royal Academy of Dramatic Art) which is where I went. When he auditioned me, he said, "Your speech, monologue, is fine. It's good. Yeah, I think you have ability but you're making it happen. Don't make it happen, let it happen." And that's a sort of subtle shift I think, as an actor.

I got to read some writings by serial killers, and they got inside my head. They were quite disturbing. I read disturbing stuff about that very detached way of manipulating people to do things.

We'd all like to believe that perhaps people could stop killing each other.

I loved doing Harry Potter. I had a great time on that. And I think it's good to have a mix. I think you're learning all the time.