Jean Paul-Sartre once said: Freedom is what you do with what’s been done to you, and America – with its freedom from Britain and other colonial powers – develop its own peculiarities, one of which is the White House Correspondents’ Dinner, a night where the press and the White House ostensibly bury their differences over a few shots. Normally those shots are jokes like Obama’s anger translator or Reagan dialling in after an assassination attempt, but this year they came from the barrel of a deranged gunman who had managed to waltz past security.