HM George I's 14-Great Grandmother. U.S. President [WASHINGTON]'s 14-Great Grandmother. PM Churchill's 17-Great Grandmother. Lady Diana's 19-Great Grandmother. PM Cameron's 19-Great Grandmother. HRH Albert II's 21-Great Grandmother. Louis XVII's 18-Great Grandmother. Poss. Agnes Harris's 11-Great Grandmother. Poss. `Osawatomie' Brown's 15-Great Grandmother.