Hitchcock is a big ask. I am playing someone significantly older than me and someone significantly bigger than me. The stuff I find very interesting is why certain physical things have come about. How can he be light on his feet when he is so big? How can his weight vary so much? Where does this rather beautiful voice come from?

Certainly for my father, there were great times, good times, not-so-good times. He might be shooting a Fellini film for six months, then not working for two months. I'm used to that dynamic.

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.

You always get told how important the premiere and doing the press is, but I have suspicions.

There is this miraculous thing I heard Hugh Grant talking about - the thing about screen acting is that you can read people's thoughts. You are trying to register something inside and usually the eyes in cinema are where you will register that.

When you're training as an actor, a lot of the big work you're learning is to treat fictional characters like real people. You don't have the problem of discovering a backstory with real people, but there's always a mystery which is common to both fictional and factual characters. They are never quite the person you think they are.

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.