If there is a banging on the flat next doors door, it means that someone has let someone past the security door when they shouldn't have. If, on opening th edoor to find out what is going on, you are greeted with a distraught looking female, react according to instinct.
If, on asking said female (of indeterminate age but looks wasted) if she's looking for the neighbour, she collapses into a sob story, pay attention to words of sob story. If she says "he paid me to have sex with him, but gave me a checque, so I can't afford to pay for the B&B tonight and I've nowhere to sleep", then turning off your normal altruistic instincts might be a good plan. Esepcially if oyu happen to know the bastard is actually in but not answering the door.
If the lady upstairs (Anne) gestures to you to run and leave it, probably a good plan to shut the door and not get involved.
FFS, I need to move out of this building. Girl claimed to Anne that a) she's 16 (she looked a lot more, um, "lived in", but was definately off her face on something) b) he'd given her a cheque for £400 (um, for sex? with that? he's stupid, but not that stupid - besides, if it's for that much, it's definately rubber, he's as skint as me, but earns (a lot) less). Spoke to Anne after she left (Mike never opened the door). She'd rung him from upstairs, he wasn't going to leave the flat. Even the girls downstairs (who, let's just say, aren't the nicest of neighbours) thought she was a problem.
Charity? Maybe it ought to begin at home. But to bring back 16 year old drug addicts and pay them for sex with a rubber cheque, and then hide from them and let your neighbours deal with it? I thought he was the decent neighbour (apart from Anne).