Harris v Sheffield United Football Club [FC] (modified) with facts as follows: The defendants (the FC) argued that they did not have to pay for a large police presence to secure their stadium during home matches. Police did not patrol inside the football club's premises and it was noted that an experienced ticket agent did check IDs of fans scrupulously against the hooligan blacklist when they attempted to buy tickets to see the game at the stadium. Those on the blacklist were turned away and not sold tickets . [a] To answer whether the promise of the FC owners is enforceable, which rule must be applied? (Rule must be based on consideration theory. Otherwise, zero marks will be awarded for the whole question set.) [b] Using that rule, is the promise enforceable? Answer YES or NO and explain making reference to relevant theory. [c] In the original case it was noted that the FC owners "had voluntarily decided to hold march on Saturday afternoon when large attendances were likely increasing the risk of disorder." Explain in what way that criticism lacks merit.