My very first friend was my stand-in, who's a very dear friend to this day, and she kind of saved my ass. She told me where to stand and where the camera was and where to look. I thought, "If I don't enjoy this, then there's absolutely no point in being an actor."

Joss Whedon writes beautiful drama. His sensitivity and his sense of drama and scenes are pretty exceptional. There's no one else writing like him, really, in sci-fi and TV. That's not to say there are no astonishing writers on TV. I was nervous about coming to America and playing an English person who speaks very English when all the writers are American, because it's a very particular thing to imitate, and if it's badly imitated, it sounds painfully contorted and silly. And he writes very well for English people. It was Joss Whedon who persuaded me.

There are movies where I've walked onto the set and felt, "This is home," and I'm confident in myself and my work, but that was my first experience of live TV. At that stage, Friends was at its unassailable height of popularity and brilliance.

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.

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."

It was fine when I was single and childless. Carrying the responsibility of screwing up your kids at the same time is huge. I remember when I got Peter Pan, and I told my mom and dad and my friends I was leaving - again, I was cast way late on - in the next two days to go to Australia for four months, and they all went "Bye! See you in four months!" But no one said "We need you," and I really knew that it was time to think about someone else for a change.

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