check with your local council as to whether they can enforce this law. The reason i say this is that our local tesco's got planning permission for extending their carpark only on the condition that the carparking space could be used by people as a general carpark and not just for tescos shopping. therefore they could not enforce their "2 hours limit" law even if they wanted to. I confronted the manager about this and he agreed they cannot do anything about people who park for more than 2 hours, even if they want to