Best thing to do if possible is to take a pic and send it to our local SNT team.

They are pretty good and very on it with local teenagers that cause trouble.

Saying that, not all local teenagers wearing these sort of clothes cause trouble, but just a few giving them a bad name, I know many that wear these kind of clothes that have impeccable manners and are very respectable to their elders.

Though If in doubt I'd call 101 or 999 depending on urgency.especially if they are returning again.