I know it's really square but I'm one of those people who piles on the factor 50 as soon as I'm outside.

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."

I used to be absolutely addicted to the gym and I do still love it.

I don't have an iPod! It's never appealed to me, really.

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.

I've had journalists beg me to please say something negative about my estate.