Nancy, the first – and perhaps most famous – of the six Mitford girls, died half-a-century ago on 30 June. The lives of the Mitford sisters seem as remote today as Jane Austen’s Bennett sisters. It is almost impossible to separate the family from their fictional equivalents. The books that made them so, Nancy’s The Pursuit of Love and Love in a Cold Climate, have become classics, still in print today, creating cult figures of her already notorious family.