Sometimes the film of an event becomes part of the history it is portraying. I first came across this phenomenon with Guy Hamilton’s The Battle of Britain (1969). The movie vindicated the strategy of Air Chief Marshal Sir Hugh Dowding and his principal air commander Air Vice-Marshal Keith Park and portrayed their rival, Sir Trafford Leigh-Mallory, the advocate of the notorious Big Wing, as at best misguided. The film-makers on the whole got it right. The Battle of Britain included a long overdue tribute to the two great airmen who had won the battle by attacking the enemy piecemeal instead…