Margaret Cavendish Harley (1715-1785), was the only surviving child of Edward Harley, the 2nd and his wife, Lady Henrietta Holles (1694-1755), who was herself the only child and heir of the 1st Duke of Newcastle and his wife, the former Lady Margaret Cavendish. On 11 July 1734, she married William Bentinck, Duke of Portland, and they had six children. Her husband died in 1761 and she was known as the Dowager Duchess of Portland until her death in 1785. She was a great collector of plants, animals and natural history specimens, as well as works of art. Her most famous acquisition was the Portland Vase, a Roman cameo glass vase which she bought from Sir William Hamilton and is now in the British Museum. The entire collection was sold at auction following her death. She gave a refuge to Elizabeth Elstob, the Anglo-Saxon scholar, whom she made tutor to her children, and also took Mary Delany to live with her after the death of her second husband. In her youth, Margaret Harley was a close friend of Elizabeth Montagu, who visited her at Wimpole Hall in Cambridgeshire. Elizabeth’s first letter to her was written when she was eleven years old and Margaret was eighteen