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.

There's not a huge pile of scripts at home. It's what happens to be on the table at that moment with your availability. And then you have no control over when these things come out.

There's something in the rhythm and roll of it that is connected to the way Hitchcock thinks and moves. Then there is everything he ingested - the cigar smoking and drinking that's imprinted on his voice.

It's always very strange to have your life dramatized because it never happens like that. Things will be different.

The prosthetics were interesting because the artist was so good that they could just put a Hitchcock mask on me, but you don't want to do that. You're an actor playing Hitchcock, so it's about how much of that you're going to do.

Best ever was filming in Barcelona last year, and I had a couple of scenes with De Niro. He's a very shy man. Speaks so quietly that people tend to bend down and adopt the same tone, almost the same voice, whenever they talk to him - watching, you'd think someone's offering to carry out a hit for him when they're just offering him a cup of coffee.

I was a fan of Hitchcock, but more importantly than that, he is such an inscrutable man, and a very carefully inscrutable man. He apparently was blank-faced with a calm and controlled presence. I was immediately anxious and thought, 'How am I going to get behind that?'