DOCTOR: Now, what year is this?

EVELYN: Oh no, not that old one.

MARY: It's Christmas, 1828.

DOCTOR: Precisely.

EVELYN: And?

DOCTOR: I realise that Robert Louis Stevenson was a genius, but even a genius would find it very difficult to write the Strange Case of Doctor Jekyll and Mister Hyde - oh, it's pronounced 'Jeekel', by the by - a full thirty years before he was born, wouldn't you say?

EVELYN: You mean Knox is a Time Lord or something?

DOCTOR: A Time Lord or something, yes. A very apt phrase. Certainly something.