Certainly as actors, and maybe as directors, you've got to hang on to something childlike. You've got to know what play is. I haven't worked with Mike Leigh, but I know him very well and there's something open in his eyes about what's in front of him. And the same is true of Alfonso in a Mexican, mad way. There's an enthusiastic response to something. Neil Jordan, the same, when he gets excited . You just want to know there's a human being in there.

Acting is about giving something away, handing yourself over to whatever role you are asked to play. I'm not hiding or escaping or seeking anonymity. I reserve the right not to have a rubber stamp on my forehead saying this is who I am. Because who I am gets in the way of people looking innocently at the parts I play.

I have a photograph at home of Fred Astaire from the knees down with his feet crossed. It's kind of inspiring because it reminds me his feet were bleeding at the end of rehearsals. Yet when you watch him, all you see is freedom. It's a reminder of what the job is about in general, not just being in musicals.

I never talk about 'Harry Potter' because I think that would rob children of something that's private to them. I think too many things get explained, so I hate talking about it.

Each character I play has different dimensions. I'm not interested in words that pull them together.

Do you know that moment when you paint a landscape as a child and, when you're maybe under seven or something, the sky is just a blue stripe across the top of the paper? And then there's that somewhat disappointing moment when the teacher tells you that the sky actually comes down in amongst all the branches. And it's like life changes at that moment and becomes much more complicated and a little bit more boring, as it's rather tedious to fill in the branches.

If you could build a house on a trampoline, that would suit me fine.