 Margaret would be the last princess born to a reigning English monarch until the birth of  who's wife? 
Margaret, Countess of Pembroke: Margaret of England (20 July 1346 – October/December 1361) was a royal princess born in Windsor, the daughter of King Edward III of England and his consort, Philippa of Hainault. Elizabeth of York:  As the wife of Henry VII, she was the first Tudor queen.
i don't know