Rule 1: The Doctor lies.

When writing comedy, you have to have the confidence to believe that there is only one type of relationship in the world, and we are all having it, that all men behave in the same way and so do all women.

Do you know how you make someone into a Dalek? Subtract Love, add Anger.

You take this cold, remarkable, difficult, dangerous, borderline psychopath man, and you wonder what might have happened to him had he not met his best friend, a friend that no one would have put him with, this solid, dependable, brave, big-hearted war hero. I think people fall in love, not with Sherlock Holmes or Dr. Watson, but with their friendship. I think it is the most famous friendship in fiction, without a doubt.

We're thrilled to have Maisie Williams joining us on Doctor Who. It's not possible to say too much about who or what she's playing, but she is going to challenge the Doctor in very unexpected ways. This time he might just be out of his depth, and we know Maisie is going to give him exactly the right sort of hell.

See the bowtie? I wear it and I don't care. That's why it's cool.

[The Doctor, Capt. Jack and Rose are cornered by the empty children.] The Doctor: Go to your room! Go to your room! I mean it. I'm very, very angry with you. I'm very, very cross! GO! TO! YOUR! ROOM! [The children lurch away and obey him.] I'm really glad that worked. Those would have been terrible last words.