In 1957 John Julius Cooper (later Norwich) was keeping open house in Beirut, ‘the Clapham Junction of the world’s air routes’.Guests were given dinner on the terrace, where the Coopers liked to watch their faces ‘as, promptly at ten minutes past nine, an immense, luminous grapefruit appeared from behind Sannine and climbed slowly up into the eastern sky’. JJ’s passions — for history, for Venice, for music — have always been enlivened by a sense of theatre: his books are erudite and entertaining. His mother, Lady Diana, took to the stage at the age of 30; she had some of the instincts of a stage manager, too, never more in demand than when she became the chatelaine of the British embassy in Paris after the war. His father, Duff Cooper, was a diplomat. JJ’s uncle, the Duke of Rutland, always had 60 or 70 people to Belvoir Castle over Christmas and New Year — JJ, as an only child, skipped merrily between the battlements and the cousins. The Coopers’ weekend guests included H. G. Wells, the Churchills, and Hilaire Belloc, who sang ancient French songs in an old, cracked voice. JJ performed, too, for pocket money: there was never any question of not including him. He was a longed-for miracle — Diana was 37 and had been told she would never have children. She once told her son that by 1916 Duff Cooper was the only boy she’d ever danced with who was still alive. Duff drank hard and toured America to drum up support for the war. When it broke out, the 11-year-old JJ found himself spirited away for safety to a prep-school in Canada, an experience he seems to have enjoyed although it kept him away from his parents for a year. Eventually he returned to Eton, where a boy’s life was still largely a Victorian pantomime of fagging and hot buttered toast. His parents got the Paris embassy job in 1944, making JJ possibly the youngest British visitor to Paris since 1939; he flew there in an RAF transport, too. In splendid contravention of publishing fashion, these are memoirs of almost unalloyed happiness, and they recreate a world which seems, on the whole, safer, wittier and richer than our own.