Du Maurier's novel Mary Anne (1954) is a fictionalised account of her great-great-grandmother, Mary Anne Clarke née Thompson (1776–1852), who, from 1803–08, was mistress of Frederick Augustus, Duke of York and Albany (1763–1827). He was the "Grand Old Duke of York" of the nursery rhyme, a son of King George III, and brother of King George IV and King william IV. The central character of her last novel, Rule Britannia, is an aging Actress, thought to be based on Gladys Cooper (to whom it is dedicated).