For those of you increasingly gripped by this primary race – that is, as far as I can tell, anyone interested in politics – allow me to recommend an essential historical primer on DVD. Robert Drew’s pioneering documentary Primary (1960) clocks in at a mere 53 minutes but tells you all you need to know about the stakes and the drama in these distinctively American contests. Drew, using only a recorder and a small camera, followed JFK and Hubert Humphrey around Wisconsin as the former moved towards the Democratic nomination. The verite style is astonishing for a film almost half a century old. But the image that stays with you is the expression on Humphrey’s face as he slowly grasps that whatever he says, whatever he does, however many interest groups he appeases, he is doomed: a generational shift is going on all around him and there is nothing he can do. That may or may not be Hillary Clinton’s fate. But this is an essential piece of cinema for all primary-obsessives.