Her doctorate was concerned with the art of letter-writing in France between 1789 and 1830. The body of materials on which she based her thesis was a mass of correspondence — 11 large volumes in all — generated by her ancestors in France and Switzerland. In the course of her researches she developed a keen interest in her family’s genealogy, and then in her husband’s. It was the horror she felt on discovering the extent of the destruction of Maxwell’s family by the Nazis that led to her work on the Holocaust.