Even while he’s having a cinematic moment, Churchill keeps his distance. Christopher Nolan weaponized celluloid machinery for the hyper-technical tension of Dunkirk, in which the politics of the coastal evacuation took place off screen, Kenneth Branagh’s naval captain standing in for the stiff upper lip of absent British authorities. Jonathan Teplitzky’s Churchill found Brian Cox’s wartime Prime Minister at the end of his tether on the eve of the Normandy invasion, tired and morose, struggling to maintain the brittle national morale. And now Joe Wright’s punchy Darkest Hour, the closest of the three to a traditional biopic, packing Gary Oldman in…