Re: Hold on . . .
I think you underestimate the MET. They will arrest you and you will then be pissed off. I don't trust these guys any further than I can throw them, but they will use the refusal as an excuse to arrest you and thereby force you to hand over your details. You can bother with the whole wrongful arrest later, but not before you have accidentally fallen down the stairs a few times and had your house turned over looking for evidence that you are a terrorist*
No, I don't like the MET and am glad I don't live in London.
*The main reason you refused to cooperate in first place, obviously...