Nineteen sixty-three was a calamitous year for Harold Macmillan. First, General de Gaulle pulled the rug from under him by vetoing British entry into Europe. Then the Profumo affair turned him – with an extra twist of the knife from the satirists of Private Eye – into a laughing stock. In October, with the Conservative party on the brink of mutiny, he fell ill and resigned. One of the few to offer words of encouragement was the novelist C P Snow. ‘Prime Ministers’, he wrote to Macmillan, ‘survive in history according to whether their intelligent contemporaries find them psychologically interesting. You are the only Prime Minister for a long time, Churchill excepted, who has evoked any such interest.’

Snow was right. Macmillan was a politician of the front rank, but many of the issues he dealt with would be lifeless on the page today without the animating spirit of his personality. When Anthony Sampson published a biography of Macmillan in 1967, he subtitled it ‘A Study