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.
Eleanor de Montfort Eleanor de Montfort, Princess of Wales and Lady of Snowdon (1252 – 19 June 1282) was an English noble. She was the daughter of Simon de Montfort, 6th Earl of Leicester and Eleanor of England. She was also the second woman who can be shown to have used the title Princess of Wales.