I once saw a bachelor/stag party getting quite drunk on a train to the point where a woman in the carriage was getting quite angry about it, reported both to the conductor and to the transport police when she got off at Carlisle, but as far as I can remember not a lot happened. Someone from the transport police did get on at Lancaster, was greeted with "Oh, sod off, son!" by the best man, he took all their details but then got off the train after that and they carried on to wherever they were changing anyway. So yeah, there's not a lot that ever gets done about it anyway.