Duke of Devonshire is a title in the Peerage of Englan held by members of the aristocratic Cavendish family. This branch of the Cavendish family has been one of the richest and most influential aristocratic families in England since the 16th century, and have been rivalled in political influence perhaps only by the Earls of Derby and the Marquesses of Salisbury. Although in modern usage the county of Devon is now rarely called 'Devonshire', the title remained 'Duke of Devonshire'. Despite the title of the dukedom and the subsidiary title the earldom of Devonshire, the family estates centre in Derbyshire. It is sometimes speculated that Derbyshire rather than Devonshire was intended on the original letters patent for the earldom, but no hard evidence supports this.