Surely there is nothing that those who hire the hall out can do once people leave the building. Even with the best run TT events there will be some idiot who will smuggle booze in, I bet a police car slowly driving past at chuck out time would help but that is asking for a miracle.
Howard, I really think you and your neighbours should start watering your front gardens on these troublesome occasions, preferably with a hose that has a strong jet
.