Poss. HM George I's 14-Great Grandmother. Poss. U.S. President's 16-Great Grandmother. Poss. PM Churchill's 20-Great Grandmother. Poss. Lady Diana's 20-Great Grandmother. Poss. P.M. Cameron's 21-Great Grandmother. Poss. Agnes Harris's 11-Great Grandmother. Poss. `Osawatomie' Brown's 18-Great Grandmother.