It's always a help when you have worked with someone as you've got to know them a bit already.

In orthodox film-making, you never shoot sequentially - but with improv, obviously every move you make has a knock-on effect; it is a cumulative process. I have improvised, on the non-scripted 'Timecode.' It can become entirely indulgent: actors smashing crockery and competing verbally.

What am I doing in this silly showbiz life? I do wonder that sometimes.

Once you get into your stride, the camera becomes like another person in the room. It's like being in a very small theatre where there is no getting away with anything because the audience is centimetres away from you.

I play the guitar. This year at the Sundance film festival, I joined the band from 'The Guitar' on stage. We warmed up for Patti Smith, and then the director Michel Gondry got on the drums to play some songs from the soundtrack to his film Be Kind Rewind with Mos Def. It was pretty mad.

When your life is as precious as all our lives are, then it needs to be kept precious and looked after and treated well. And that is not something we should be sharing with a wider audience.

I had a happier experience of the city as an actress than I had had as a model.