IAN: Well, you see Vicki, our space ship, well, isn't like this one. It travels through time.

BARBARA: We left in 1963.

VICKI: 1963! But that means you're about five hundred and fifty years old.

BARBARA: Why, yes, I suppose I am. Yes, it's a way of looking at it, but I'll try not to look at it too often.

VICKI: They didn't have time machines in 1963, they didn't know anything then.

IAN: Oh, we weren't entirely ignorant, young lady. Even the Doctor thought it was worth paying us a visit. That's how we got mixed up with him in the first place.