MICK wrote:

Personally i would get these scrape their knuckles with a cheesegrater and dip them in Vinegar........ or press drawing pins under their Fingernails................

I am taking notes! May come in handy one day.

Did you ask the store for any CCTV? They probably can't be bothered or will have some policy against it, but worth asking. If the muppet with the pram was in a car, you may get the reg. which you can then apply for an address for (for £5 or so if it's in connection with an accident). Or once identified, be at the store at the same time next week. People get into strict habits when it comes to shopping, so you have a chance to spot them. The rest is up to your imagination/conscience/temper.