Isabella Fitzwilliam

Isabella Fitzwilliam was the wife of Sir Ranulf Fitzwilliam and the mother of Hugh Fitzwilliam. 

She was imprisoned in the dungeon by Sir Gilles Estram to ensure her husband's obedience to King John. The Master later freed them, claiming that the Doctor was manipulating the King. 

_{Biography from the Tardis Wiki article, licensed under CC-BY-SA}