Margaret would be the last princess born to a reigning English monarch until the birth of  who's wife?
Elizabeth of York Elizabeth of York (11 February 1466 – 11 February 1503) was queen consort of England from 1486 until her death. As the wife of Henry VII, she was the first Tudor queen. She was the daughter of Edward IV and niece of Richard III, and she married the king following Henry's victory at the Battle of Bosworth which started the last phase of the Wars of the Roses. She was the mother of King Henry VIII. Therefore, she was the daughter, sister, niece, wife, mother, and grandmother of successive kings and queens of England.
Peter Phillips Peter Mark Andrew Phillips (born 15 November 1977) is the elder child and only son of Anne, Princess Royal, and her first husband, Captain Mark Phillips. He is the eldest grandchild of Queen Elizabeth II and Prince Philip, Duke of Edinburgh. After graduating from university in 2000, he worked for Jaguar followed by WilliamsF1. In 2003, while working for WilliamsF1 in Canada, he met Autumn Kelly, whom he married in St George's Chapel at Windsor Castle in 2008. For many years Phillips has worked in the sports sponsorship and management fields. He is currently 13th in line of succession to the British throne.