We're interested by public personas and private personas, otherwise we wouldn't put on with actors rambling on with the same kind of stuff, over and over again, saying variations of the same thing. I'm always amazed by how fascinated people still are by actors because it's the same version of events that actors describe, all the time.

I'm very interested in people, so if a character happens to be real, there's that much more to look at.

When I told people I was going to be doing the movie and the voice of Dobby, they were kind of awestruck, the people who knew about Harry Potter. I felt rather guilty that I didn't really understand the scale of the job I was about to take on. Now, I am well aware of what I'm doing, and actually, it feels a very serious acting responsibility.

But I think the children of actors share a certain pragmatic approach. One is denied some of that 'running away with the circus' element of being an actor.

They know you're not Alfred Hitchcock, but you need to be enough Alfred Hitchcock for them not to be bothered by it. That's a reassuring thing.

I had to change the shape of my own voice. It was quite hard to pull off and so once I had it, I stayed in Hitchcock's voice all day on set.

Hitchcock's got a very interesting voice; it's a very controlled, measured rhythm that's quite slow and, in that sense, also felt quite controlling in its pace. He retained something from his childhood, that London sound, as well as adopting some of the L.A. sounds... All of this helps you create the character.