My friends have always called me 'Mr. Thorough,' in that when I get into something, I become obsessed with it.

Everyone on the set has a mobile phone, and I found by pushing a few buttons, they could be programmed into different languages. I fixed Robbie's Coltrane to speak in Turkish.

I'll say American for now. I really have no preference, though. Nationality is nothing. It's all about the girl - but she has to be curvy!

Fame is damaging when people become reliant on it for their sense of self, and their identity, when fame is linked to how you see yourself.

I want to write and direct, but I don't think if I did it for 100 years I would ever come close to putting something out there that gives a feeling of all-encompassing and joyous.

There is always this thing of will you get too old for your part? But people are playing a lot younger than they actually are in real life. I don't think it's as big an issue as a lot of people are making it out to be.

Harry Potter star Daniel Radcliffe has confessed that until recently, he thought the 16-year-old fellow tween idol [Justin Bieber] was a female. 'I only heard Justin Bieber for the first time two weeks ago. I genuinely thought it was a woman singing. I'd never heard it before. Is it big in England yet?'