Similar thing happened to one of my vans last year,some drunk twat and his divvy mate were pulling the wing mirror and number plate off.unfortunately for them my dad happened to be walking past with the dog,and being of the old school did nothing more than walk off and punched one of them right in the face.the other one ran off and left his pal crumbled on the floor in a heap.my dad phoned me and I made my way there,an hour later I arrived to see the damage and the bloke was still on the floor
He was in his twenties and should have known better.but thats England these days...
I hope the old bill catch your vandals,I wouldnt hold your breath though.