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'm quite happy to leave it still feeling that way, leave it before it starts feeling like a job. ... I have such fond memories of watching 'Doctor Who' when I was a kid and growing up, that if I've left anybody anywhere with memories as fond, then I feel like I've done my job.

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.

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

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.

I mean, you know, while I'm acting on stage I'm ranking quite high, but in a room with Barack Obama I'm probably into negative digits. I never feel very famous.

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