I'm not very glamorous.

David Tennant is a massive fan, and grew up dreaming he would be the Doctor Who one day. So I did feel, when I first got the job, "Right, now I've got to do loads of research into absolutely everything Doctor Who." But that's not possible to do in a short space of time. So my knowledge has been growing and developing as I've been doing it, and that's been fine. That's been appreciated by the fans, and the executives never expect me to be brushed up on absolutely everything.

Whether people watch Doctor Who or not over here, everybody knows about it. It's a British icon, it's so part of the nation.

I'm not very glamorous.

I found a lot of comfort in the fact that 30-odd people have been companions before me. I think that when there are so many people contributing so many things to the show, all you can do is make it your own. You can't try to emulate anyone, because who would you pick? The companions are very much the everyman, and the audience watches the story through their eyes, so they could be the person next door. And everybody's different.

Being short works for me.

I was very much into science when I was young - I wanted to be a marine biologist, then I wanted to be a doctor, and then something else, I was always changing. Acting didn't come up until much later, probably about 16 or 17. I thought, "Oh, I quite like this."