A fair amount.

[She isn't about to break any news when she doesn't have any answers of her own.]

Can't quite say, not until I ask a few questions too. You worked in the Ministry, Percy, you know all the laws about Time-Turners, don't you? [Hypothetical question.] The City mucks around with time, so I've got to ask when you're from.

[Pause.]

Of course, given that you're actually talking to me and want to save your baby sister from this awful place— [She manages to keep the mocking from her voice, actually, it's just sort of matter-of-fact.] —I think I can guess.