Standing on Capitol Hill surveying the sea of faces stretching out towards the Potomac River, Steven Spielberg, the film director, said: “I couldn’t afford to do this shot in a movie.” It was, indeed, an unrepeatable moment.

There were interludes that could have fitted quite nicely into a Spielberg movie, such as when Barack Obama walked on to the podium to be greeted by a deafening roar of approval from a vast crowd of people that appeared to render even him momentarily thunderstruck.