Getting the call to be in The Goblet of Fire was like being welcomed into the most exclusive upper circle of some elite actors' club. You sit on set with the cream of the National Theatre and the RSC, all clutching wands or wearing witches' hats.

It has to be said that the bad guys are often more interesting than the good guys because you get to indulge part of your nature that hopefully gets subsumed most of the time. But I just like playing interesting characters, and variety's the spice of that, as it is with life, I suppose.

If you speak in a different accent, you begin to move in a slightly different way. You think in a slightly different way. It's part of trying to find what makes a character.

And the very fact of how you speak somehow influences who you are. The way you move, the way you think, it seeps into your being, and it's quite hard to really break that down entirely.

An accent has to do with the way your mouth works and the sounds that come out of your head, but somehow it informs everything about you.

I always like seeing people transforming themselves, in whatever way that might be, and a different accent is part of that.

I've always been a geek and slightly awkward… slightly umm… I was never the cool kid at school.

Twitter! It's like being stalked by committee!

I think it would be self-indulgent to go, Oh, I'm going to make this character different by giving him a quirk of some kind. I don't think that serves the story, particularly. But even very similar scenes with a different set of actors, a different set of circumstances, it starts to evolve as a different character.

Some people live more in 20 years than others do in 80. It's not the time that matters, it's the person.

When you're playing a real person there's a balance between playing the person in the script and playing the person as he was in life. You have to be respectful and true to who that person was, but at the same time tell the story in the film.

I think doing different accents is part of the job of acting, really. It's something else that I quite enjoy the challenge of, to be honest.

To have someone who's got a strong individual voice that is allowed to be heard is quite increasingly rare. These people need to be cherished.

I often stop when I'm doing something, in the middle of rehearsals or some other job, and I try to take a minute to think Okay, this might be as good as it gets, so drink it in, appreciate it now. So far, I've been lucky because another job has always come along to equal the last.

I'm a good person, I hope. But I'm never as good as I want to be, never as nice as I want to be, never as generous as I want to be.