The police don't usually release details until someone is charged. Eg, all the press releases about this dutch chap say simply 'a 32 yr old man', up until the latest one where the news is that he has been charged, which names him. (I can't find the Chris Jeffries press releases to double check, but I wouldn't have thought the police named him).
The info the papers get after someone is arrested is more likely to have come from neighbours, electoral roll, all sorts of places. I mean, the press know what house is being searched, it's not hard to find out who lives there.
