 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, Countess of Pembroke:  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. Elizabeth of York: Elizabeth of York (11 February 1466 – 11 February 1503) was queen consort of England from 1486 until her death.
i don't know