HM George I's 15-Great Grandmother. U.S. President [WASHINGTON]'s 16-Great Grandmother. PM Churchill's 20-Great Grandmother. Lady Diana's 20-Great Grandmother. PM Cameron's 22-Great Grandmother. Louis XVII's 19-Great Grandmother. Gen. Pierpont Hamilton's 21-Great Grandmother. Poss. Agnes Harris's 13-Great Grandmother. `Osawatomie' Brown's 19-Great Grandmother.