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

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.

As I was getting into the helicopter, a slightly nervous actor said to me, "Whatever you do, don't say to the helicopter pilot, 'Show me what this baby can do.'" So I of course, got into it and said, "Show me what this baby can do." And we just had this insane helicopter ride. It's the sort of thing you only get to do on movie sets. I'm so lucky to have done it and have that chance.

We had an ancient Russian acting coach at my drama school who said the worst offense you could commit was to let your subtext show. That is the point of acting, is to be saying one thing and not be allowed by society or your predicament to show what you're really feeling. In a way, I think that's why the therapy generation has killed script writing, because all you ever get is people going, "Hi, I'm feeling really angry right now."

When Roman Polanski did give you a "Great, great, great!" you were just like, "Thank you, Lord, for this magical moment."

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.

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