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.
Princess Catherine Ivanovna of Russia Princess Catherine Ivanovna of Russia (Russian: Княжна Екатери́на Иоа́нновна ; 12 July 1915 – 14 July 2007) was a great-great-granddaughter of Tsar Nicholas I of Russia and a niece of King Alexander I of Yugoslavia. She was the last member of the Imperial Family to be born before the fall of the dynasty, and was ultimately to become the last surviving uncontested dynast of the Imperial House of Russia.