The idea of transformation - playing something I'm not - is the bit I enjoy most about acting.

In the movie, you have to decide as an actor how you are going to give a character presence. You can't really move, walk, and talk like yourself. This creates something so you have to find something "other".

I just invited close friends and family, the usual suspects whose opinion I value but who I know will enjoy the film [Before I Go To Sleep]. I don't know how difficult it is for them to suspend their disbelief because they obviously know me and what they're seeing is not me.

Rowan Joffe was on top of everything. He knew exactly how he wanted everything to be, right down to the fact when I made those telephone calls, I didn't do it afterwards in a studio. I think that's how he operates. He likes it to be as real and as clear as possible.

I have an enormous amount of respect for Nicole Kidman. She's just done so many great movies and she's been out there at the forefront of carrying films and being a movie star. On set, it really pays dividends because when you're performing with her, she knows exactly how to play it. You don't have to compensate for her in any way.

My mother moved abroad when I was 11, my dad wasn't around from the time that I was a baby, so I was not the product of a family, but a product of observation - of watching what went on around me, of watching who I liked, what I didn't like, what I thought was good behaviour and what I thought was bad behaviour and tailoring myself accordingly.

The Secret Service I'm really excited about because Matthew Vaughn directed it. I've done a couple of movies with him - Stardust, which is one of my favorite films, and Kick-Ass, which is just a crazy, wonderful movie.