I used to go to the gym regularly and swim an awful lot, but that was when I was unemployed and knew leisure intimately.

At school I briefly wanted to be a palaeontologist, but I was no good at chemistry and physics.

That's what makes characters interesting. If Sherlock [Holmes] had started out being a straightforward man, we wouldn't be talking about him now. If he became one, that would be interesting. But you have to give him somewhere to go, as [Conan] Doyle did.

When I was your age — about, ooh, a thousand years ago — I loved a good bedtime story. The Three Little Sontarans. The Emperor Dalek's New Clothes. Snow White and the Seven Keys to Doomsday, eh? All the classics.

I don't care what other people think any more about me writing my own parts.

Sci-fi and fantasy used to be a TV staple throughout my childhood. Then it just stopped dead. It was seen as culty, a minority interest.

It's a cliche, but it's true that all the fun lies in baddies, grotesques and comic roles.