Dorothy Bentinck, Duchess of Portland
Dorothy Bentinck, Duchess of Portland (née Lady Dorothy Cavendish; 27 August 17503 June 1794) was Duchess of Portland as wife of William Cavendish-Bentinck, 3rd Duke of Portland, the Prime Minister of Great Britain. She is also a great-great-great-grandmother of Queen Elizabeth II through the queen's maternal grandmother. Biography. Dorothy Cavendish was born on 27 August 1750 to William Cavendish, 4th Duke of Devonshire, the Prime Minister of Great Britain and his wife Lady Charlotte Boyle, 6th Baroness Clifford. Marriage and children. On 8 November 1766, Cavendish was married to William  Cavendish-Bentinck, 3rd Duke of Portland. They were parents of six children: According to newspaper accounts, she was the mother of nine children, only four of whom were living at the time of her own death. Later life. The duchess died at her home, Burlington House, Piccadilly, and was buried in St Marylebone Parish Church, Marylebone, London. She “died of a bowel complaint, which she had been subject to for many years, and which terminated in a mortification after a short illness. It was at first suspected, from the violent inflammation in her bowels, that her Grace had eaten water -gruel out of a copper saucepan not properly tinned; but this suspicion is certainly erroneous, as it proved on examination.” Bentinck is a great-great-great-grandmother of Queen Elizabeth II (see ancestry of Elizabeth II)