Until 1603 the English and Scottish Crowns were separate, although links between the two were always close - members of the two Royal families intermarried on many occasions. Following the Accession of King James VI of Scotland as King James I of England to the English Throne, a single monarch reigned in the United Kingdom.

The last four hundred years have seen many changes in the nature of the Monarchy in the United Kingdom. From the end of the 17th century, monarchs lost executive power and they increasingly became subject to Parliament, resulting in today's constitutional Monarchy.