I think it will be, as always, interesting to compare different portrayals of Hitchcock. I'm very honored that I'm playing the same part as Anthony Hopkins.

You're playing a character in a drama who happens to be based on someone who existed. It's never going to 'be' that person, but it's based on someone well-known, and you want to create enough of that person for it not to be a distraction.

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.

I still don't feel I know Hitchcock at all. I find that the more one looks, the more elusive he becomes. But my admiration for Hitchcock the filmmaker remains undiminished. He is a giant of the cinema and the darkness in him informs his cinematic language. You can't separate one from the other.

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.

One key element to Hitchcock is the drooping jowl. That was crucial because his silhouette is crucial. There is something about his silhouette that became his brand.

If you ever have the good fortune to meet Tippi Hedren, she's an amazing woman. You can't quite believe she is the age she is.