Diana's letters to her only son, John Julius Norwich, cover the period 1939 to 1952. They take us from the rumblings of war, through the Blitz, which the Coopers spent holed up in the Dorchester (because it was newer, and therefore less vulnerable, than the Ritz), to rural Sussex where we see Diana blissfully setting up a smallholding as part of the war effort. After a spell with the Free French in Algiers, Duff was appointed British Ambassador to...