You’ve seen a lot of the world beyond Oklahoma now. you must be a very different person to the all-American boy who set off to Hollywood…

"I remember when we were filming Ocean’s Twelve in Amsterdam and it was strange to me because, you know, we’re used to being American and people wanted to come here for the opportunities. But the perception of America had changed.

"I get a bike wherever I go and I was on this pedal bike, riding around. I had left the guys and was going for a midnight ride around Amsterdam and there were some guys coming out of a bar. They were trashed, having a good time. I said, “Excuse me” and swerved out of the way, and they started screaming: “You fucking American! We’ll fucking kill you!” I’d never come face-to-face with that turn in our public perception."

You’ve also travelled a lot with your environmental work. does being a celebrity help you achieve your goals or is it an obstacle to getting people to take you seriously?

"That’s a good question. Of course it helps because there’s a spotlight on us. It’s opened many doors and you can get access to meeting a lot of great minds. Where it hurts is… Well, it doesn’t hurt. It’s just important that when you take something on, you stick with it.

"Hollywood has a reputation of being flighty and self-serving, so it better be something you believe in enough to stick with."

OK, let’s end on a bright note. You were great in Johnny Suede and Burn After Reading. Can we expect to see you in more comedies?

"I do like a comedy. There’s some great comedy coming out in America – I’m thinking of Zach Galifianakis, Jonah Hill, Danny McBride…

"But the point is just to keep messing it up. I figure I’ve only got so many more of these [films] I get to do, and I wanna make sure they have some… worth, to me."