Lady Diana Cooper was a celebrity in her day. As her son John Julius Norwich writes in the introduction to this book, she had ‘quite startling beauty’ and glamour. Since coming out in 1911 (she was born in 1892) she had been the darling of London society and the star of the so-called Corrupt Coterie of pre-1914 gilded youth. Almost all the men who adored her were killed in the First World War. In 1919 she married one of the few survivors: Duff Cooper, the son of a VD doctor, a clever Foreign Office man with a DSO.

Duff was the centre of her life. It was she who made the money, playing the Madonna in Max Reinhardt’s mime play The Miracle, which ran for six years. This earned enough for Duff to quit the Foreign Office and realise his ambition of becoming an MP. Thereafter Diana devoted her life to Duff’s career. Wherever Duff went, Diana went too. She accompanied him on wartime missions to Algiers and Singapore, braving terrifying flights in bumpy planes. Duff was chronically unfaithful, yet his mistresses – Louise de Vilmorin and Susan Mary Patten, who had a child by him – became Diana’s good friends. Diana had admirers – male adoration was a psychological necessity for her – but these relationships were always platonic. It was a curious marriage, but it worked.

In 1940 Duff was appointed minister of information in Churchill’s government. The 11-year-old John Julius, their only child, was evacuated to Canada. Diana stayed in England to be with Duff but wrote to John Julius often and at length. Sitting in bed, bolt upright and cross-legged, using pencil (because ink