On her death, the Marquessate became extinct and the Barony passed to her eldest daughter, Amabel, Lady Polwarth (widow of Alexander, Lord Polwarth, eldest son of the 3rd Earl of Marchmont), who became 5th Baroness Lucas. In 1816 she was created Countess de Grey, of Wrest in the County of Bedford, in the Peerage of the United Kingdom, with a special remainder to her sister (the widow of the 2nd Baron Grantham) and her heirs male. (See Earl de Grey for information on that peerage.)