Kazamb. The answer would be as many as PAS have spare to cover such things as scheduled and unscheduled maintenance, I'm sure someone could come up with the actual figure though.
I would think that the ne'er-do-wells who did this were thinking that police 41 would be out for several days so they could have some breathing space to commit their crimes without the spy in the sky looking for them, instead of the several hours it actually turned out to be