The history of Spanish–British relations is complicated by the political heritage of the two countries. Neither the United Kingdom nor Spain has a unique constitutional ancestor; the United Kingdom was originally created by a union of the kingdoms of England and Scotland (and later joined by Ireland), whilst the Kingdom of Spain was initially created by a union of the kingdoms of Castile and Aragon. They have also been complicated by the fact that the United Kingdom and Spain were both imperial powers, after the same land, an occurrence which is being played out to this day with the disputed ownership and status of Gibraltar.
