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. Margaret would be the last princess born to a reigning English monarch for over a century, until the birth of Elizabeth of York in 1466. She was also known as Margaret of Windsor.
Margaret Stuart (1598–1600) Margaret of Scotland (Margaret Stuart; 24 December 1598 March 1600) was the second daughter of King James VI of Scotland by Anne of Denmark, daughter of Frederick II of Denmark. Sometime in March 1600, Margaret died of an unknown illness and she was buried in the now ruined Abbey of Holyrood. Three years later, her father ascended the throne of England.