It is a matter of notifying the Council each year with the dates that the "campsite" will be in use. So the case of a pub, as an example, they could notify the Council that they will operate the "campsite" every Saturday night that year. They would also need to give adequate information on the facilities available, e.g toilets and waste disposal. If those requirements are satisfied the Council cannot object as it would be classed as "permitted development". There are exceptions, e.g. a pub that is a listed building wouldn't be able to use the "60 day" rule. There are also means by which the Council could prevent any pub within a prescribed area from benefitting from the rule, but they would have to go through a formal legal process to achieve this.