Exactly what I would do! 'Excuse me mate can you just quickly come have a look at this? Yeah it's my camera that I put up after the first time my car got keyed, it also has a few pictures of you doing it. Not saying you did it the first time (but you probably did) but there's two ways to go now: you pay me the damage and I refrain from doing whatever it is that's upset you. Or, I phone the police and you can pay damages + the £100's in court fees?'