Britain’s first McDonald’s didn’t crash-land in the West End with celebrity flashbulbs. It slipped into Powis Street, Woolwich, in the autumn of 1974. The launch had a curious pageantry. Radio 1’s Ed “Stewpot” Stewart and Len Squirrell, the mayor of Greenwich, cut the ribbon. A commemorative plaque declared the store McDonald’s 3,000th worldwide, dedicated by Robert Rhea, Fred…