Working with Roman Polanski is funny. It's like anything in life - someone warns you that something's going to be amazing or difficult or awful, and you say, "I can do that. I can cope with that." And then when you're in the middle of it, it may be joyful or tricky, but it's never difficult in the way you think it's going to be difficult.

There's this absurd situation on a movie set where your trailer's here and the set is here and the lunch tent is here, and you're not allowed to get yourself from these three places.

Ewan McGregor and I said this to each other after we saw The Ghost Writer. Every time Roman Polanski did a "No, no, no!," he was right. It was really as if a sculptor was asked to sculpt the embodiment of despair - that was the attitude he would strike. But as with every sort of inspiring teacher you ever had who was strict and scary, when you get it right, the sun comes out, and it's worth it.

That was a bizarre and unlikely event, which has misled a generation of drama students from my old drama school that dreams really do come true. I was an unemployed actor. I had been an actor for about eight years, and had worked in theater, and done a tiny bit of TV, and somehow an audition video of mine ended up on Kevin Costner's television screen, and he rang me up and invited me to fly first-class to Hollywood and be in his movie The Postman.

The trouble with audition process is, when you're an unemployed actor, it's the only time you get to act, and it can be quite fun. If you feel in control of the material and you feel that the people are pleased to see you and are excited by you auditioning for them, it can be a really rewarding process. But it can also be a very humiliating process.

My husband Rhashan reminds me of my father because he's got great strength of character.

When the Hollywood thing happened, I thought at some point I'd get to the front of the queue: 'Yes, hello, I'd like to play that role.' But you don't. You just join a different queue.