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.