The Du Mauriers, Just As They Were tells the story of five generations of this remarkable family, beginning with Mathurin-Robert Busson, a master glassblower who immigrated to London in 1789, added the suffix 'Du Maurier' to his name, and so became a 'gentleman glassblower'. His three English-born children relocated to the continent, becoming respectively a doctor of philology in Hamburg; the governess to the daughters of a Portuguese statesman; and an aspiring inventor who married a daughter of the courtesan Mary Anne Clarke. This latter's son was George Du Maurier. He was born in Paris in 1834, then went to London to study chemistry and finally took up the beaux-arts in Paris, Antwerp and Düsseldorf. Later, he established himself in London as a beloved Punch cartoonist. In his last years, George Du Maurier wrote and illustrated three immensely popular semi-autobiographical novels. Of his children, the youngest Gerald Du Maurier became a prominent actor-manager, and Gerald's second daughter was the novelist Daphne Du Maurier.

In the course of her career Daphne published four volumes of family history, culminating in the extensively-researched Glass-Blowers, which revealed her French forebear's aristocratic imposture for the first time. Daphne identified with her Victorian grandfather, sharing his love of France and deep interest in family history. However she puzzled over his first book, Peter Ibbetson, wondering why he had portrayed their ancestors as aristocrats. The reason is complicated, highly revealing, and would almost certainly have been a complete surprise to her.