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.

I studied Hitchcock a little bit at University and knew the famous story about the Birds - that he'd tortured Tippi for a day using real birds. I had no idea that it was a five-day onslaught and that it was the tip of an iceberg that carried on through to another film.

I heard about the project over a year before we began. My American agent said, 'Oh, you might want to read 'In Cold Blood' because they're talking about you for Capote, but the script's with Johnny Depp and Sean Penn at the moment.' So, these things take their time to dribble down the food chain.

They seem much rarer now, those auteur films that come out of a director's imagination and are elliptical and hermetic. All those films that got me into independent cinema when I was watching it seem thin on the ground.

Four hours of prosthetics every morning, the jowls and the nose, and it was very hot so they're having to attend to it all day, and you're still petrified of so many things, such as, can I speak properly? Hitchcock never quite lost those East End vowels, even though he had the softened California consonants.

I teach for the Book Trust, which promotes reading and writing with children.