Because I was always a fat child, I got fatter and fatter, and I ended up 18 stone and with a 40-inch waist.

Doing Prometheus was what you imagine being an actor is like when you're five. In a spacesuit, on another planet, getting killed by an alien. It was a real treat, it felt like being a part of movie history.

I never mind talking about my dad. I'm proud of who he is, and being his son is one of the things I'm most proud of. To be constantly compared to someone so brilliant, who happens to be your dad, is cool.

I watched what I ate for a bit and did a bit of exercise. I wanted to look alright because I knew I had to take my clothes off and I knew I was starring alongside some extremely attractive women! I think it was Humphrey Bogart who said that the only reason people found him attractive was because of the attractive women he played opposite. So, as audience member you go: "Well, if she would find him attractive, then surely I must too!" Playing opposite beautiful actress of the calibre of Rose Byrne and Anna Faris is amazing - it does a lot of the work for you.

I think one of the main differences between being an English actor and being an American actor is that we have things like the class system in England.I'm middle class. But I've got what some people might consider to be a working-class accent, so you've got those sorts of elements in this country to consider, which, in America, exist, but not necessarily in the same way.

When you do a film, you get picked up in a car, lunch is free. Theatre is really hard, and you get absolutely no money.

You do stuff that gets a reaction and you think 'that's a winner' and then it never sees the light of day. But the thing with improvisation is that 90% of what you come up with won't be used and for good reason. But you keep going for the occasional gem that you might come up with. You do a scene and a lot of the time. We wouldn't cut. So, you come up with something that might be funny and then you go, 'alright, what else'? So, you kind of throw stuff against the wall and see what happens. But you've got to be prepared to make a fool of yourself.