Duke of Devonshire a separate title from that of Earl of Devon, which still belongs to the Courtenay family. The fifth Duke and Duchess of Devonshire are portrayed in the 2008 film "The Duchess" directed by Saul Dibb. The film is based on Amanda Foreman's biography of the scandalous 18th-century English aristocrat Georgiana Cavendish, Duchess of Devonshire (portrayed by Keira Knightley) and her relationship with the Duke (Ralph Fiennes) and his next wife, Lady Elizabeth Foster. Along with Jane Austen, the fifth Duke and his second wife appear, soon after Georgiana's death, in "Jane and the Stillroom Maid", a murder mystery by Stephanie
Mary Cavendish, Duchess of Devonshire Mary Cavendish, Duchess of Devonshire Mary Cavendish, Duchess of Devonshire, (29 July 1895 – 24 December 1988) was the Duchess of Devonshire from 1938 until her husband's death, and dowager duchess thereafter. She was born Lady Mary Alice Gascoyne-Cecil in Hatfield, Hertfordshire, the daughter of James Gascoyne-Cecil, 4th Marquess of Salisbury. She was married on 21 April 1917 to Edward Cavendish, Lord Hartington, who succeeded his father as 10th Duke of Devonshire in 1938, whereupon Mary became Duchess of Devonshire. She was Mistress of the Robes to Elizabeth II from 1953 to 1967 and Chancellor of the University of Exeter