 His sister, Princess Friederike of Hanover married Paul I, King of the Hellenes.He was born a Prince of the United Kingdom of Great Britain and Ireland.Patrilineal descent, descent from father to son, is the principle behind membership in royal houses, as it can be traced back through the generations - which means that the "historically accurate" royal house of monarchs of the House of Hanover was the House of Lucca (or Este, or Welf).