(As they run down the stone staircase, Ace stops at a Gainsborough-like painting of a lady.)

ACE: Professor, that's me.

DOCTOR: What? Gosh, so it is. My goodness, what a good likeness.

ACE: How come I ended up here?

DOCTOR: Well, it hasn't happened yet.

ACE: But it's two hundred years ago.

DOCTOR: I know. We haven't done it. That's why you don't remember it.

ACE: It doesn't make sense.

DOCTOR: Well, it did to Louis Armstrong, but then he really understood time.