I went to meet Joe Johnston, the director, and he's charming. I've been very lucky. Most of the directors I've worked with are charming. But Joe's a particularly charming man, and he showed me lots of designs and, rather memorably, welcomed me to the Marvel Universe.

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.

I've got to tell you, I've played real characters before and people always bring up this word 'impersonation,' and I'm never entirely sure what it means.

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.

What happens is some of the characters I've played have voices that are so different from my own, that it would be ridiculous if I would dip in and out of that voice in between takes to ask for a coffee, or something. Or to gossip about whatever was going on.

All of these red carpet events may seem natural for you journalists, but it doesn't feel natural for actors.

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?'