Back in 2005, when I was Christopher Eccleston, we saw one of the largest increases on record, of CO2 in the atmosphere. Unless we keep the rise in global temperature to under 2 degrees, by the time I'm Daniel Radcliffe or wee Jimmy Crankie, I won't be able to save the planet. I won't be here to help you -- well I might, but I'll be that bloke who won Any Dream Will Do.

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.

I was always going to act, literally ever since I was tiny. In fact, I have Doctor Who to thank for that. I wanted to become an actor after being obsessed with Tom Baker, the fourth Doctor Who, in the 1970s. His was the definitive performance of all time in anything.

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.

We seem to spend a lot of our time in very small spaces spouting a lot of dialogue very quickly.

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.

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.