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'm not a writer, inherently. Most of the writers I've met have stories they need to tell. I don't have that. I'm an interpreter. I like getting a script, seeing a character and thinking, "Oh, wow, I know what I can do with that."

Interestingly, this character [Doctor Nash] is probably closer to me than somebody like the evil Sir Godfrey in Robin Hood or Lord Blackwood who wants to take over the world in Sherlock Holmes. This is a character that's English, he's based in London, and so it's closer to me than a lot of stuff I've been doing recently.

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.

[Before I Go To Sleep] script was a great journey with all the twists and turns that were kind of unexpected. I had to finish the script, and I thought if we can emulate this in the film, it's going to be a really good film.

And I think in your 40s, you land a little bit, physically and mentally, you arrive at a place where you feel you've learned some stuff. Having children at that point meant I had something very useful to do for the next 20 years.

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.