Last year at the Shoreham air show, my mate had a scanner, hand held, and had a copper standing next to him listening to it in the field they use as a car park. He was impressed, especially by the controller saying how much he enjoyed seeing the B17 and always brings a lump to his throat before wishing them luck flying home. Copper said he didn't think they were allowed to chat like that and thought RT was a lot stricter.!!!
The authorities are far too busy with other more consequential matters than trying to "foxhunt" people using scanners to listen illegally to transmissions.
Last year at Eastbourne, the police sent out radio messages saying there had been a UFO landed at Beachy Head and even provided bright lights that shone in the sky there. When the cars(public) turned up they were pulling everyone of them seeing if they had scanners as they were doing a purge on members of the public who listened in. They got quite a few as well i remember. At least 20 got caught with a portable scanner.