Elizabeth Cavendish was initially Lady Elizabeth Christiana Hervey .
Elizabeth Cavendish , Duchess of Devonshire ( formerly Elizabeth Christiana Hervey , later Lady Elizabeth Foster ) , ( 13 May 1759 - March 30 , 1824 ) , is best known as the close friend of Georgiana , Duchess of Devonshire .
Elizabeth Cavendish, Duchess of Devonshire