Carey Mulligan is completely self-possessed. She knows what she's doing, and again, quite like the big-hitters I was talking about, my job was just to feel and reflect back the amazing performance coming my way. If anything, I was slightly pathetically flying in her tailwind. She's an extraordinary actress.

Roman Polanski actually said as much to me once. He had his head in his hands, and I said, "Roman, I've got to tell you, as an actor, seeing the director with his head in his hands... Look, I really want to do what you want me to do." And he went away and he came back, having obviously thought about what I said. And he said, "When my head is in my hands, I'm closing my eyes and trying to remember what I saw in my head, before any of the stuff."

The phrase you usually hear after a cut is "That was great. Perhaps we could have another go. Maybe try it this way." Even that much direction is prefaced with a lot of praise and encouragement. It's quite like how you deal with toddlers: positive reinforcement, and then a little suggestion that you might want to try something different. Roman Polanski will stop the take and shout, "No, no, no!" Which is somewhat alarming the first time it happens.

I thought "I've coped with some crazy situations, and I can do this." But working with Roman Polanski is so different from the fashionable and accepted way of directing now.

I'm a mixture of Anglo-Saxon, a bit of Spanish and one-eighth American. I've often wondered if I have an Asiatic ancestor from the East as well because I have deep-set eyes. Make-up artists are constantly trying to shade my eyelids, and I have to point out that I don't have any!

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

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.