I think there's a tendency in England, when you look at the past, to either have upper middle class period drama with its own rules, or if you're going to look at working class people, you have to do that in a particular 'Isn't it a shame, aren't they oppressed' way, or it's treated comically.

I write about what worries me and, hopefully, things worry me a little bit earlier than they do some other people, purely because I am a writer and it is my job to go out there and be worried by things.

I think there is something about a good person doing bad things for what they consider to be a good reason. Then the battle is on to almost prove to the audience that it's justified. How far can you go with that? How far can that character go before people won't accept it? Trying to walk to edge of that line is a challenge.

Locke' is a different way of making a film as well as being a different sort of film.