I had the best teacher in the business. Kevin Costner was my teacher. I was acting opposite him and he was directing me. The way he directed me, for which I am eternally grateful, is he would watch the scene back on the monitor, which is sort of considered unfashionable - you're not meant to watch yourself. But he was like, "Come around. Watch this. See there, you're doing a great reaction, but you're doing it out of frame." That was exactly what I needed. I learned how to act on film from him.

Family holidays and weekends are really brightly colored memories, full of my mother and father, rather than our nannies and au pairs.

My agents were like "Come to L.A., we've got meetings for you." I was like "No, I'm doing this now." Then my father became very ill back in England, and I didn't want to be away. I went back to England and did a bunch of crazy indie movies, all of which I loved with a passion, and none of which did any business.

I tried not to get too addicted to reading the Whedonesque website, because it could become obsessive. They were a charming and loyal bunch of people to whom I'm eternally grateful.

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.

I really needed to have something in my life, because I realized there were other things more important than my career. So I love having my children and my family.

The excruciating moments of drama are when people are allowed to show or say what they feel.