Analysis: Should the U.K. Have a Codified Constitution? . 07/02/22 The U.K. is a rather odd case of a country that's constitution is a 'mish-mash' of different sources. It was established in 1215, when the Barons forced King John to accept the restrictions that Magna Carta put forward. The main sources that make up the constitution are: Parliamentary Statues (Acts of Parliament), Common Law, Conventions, Customs and Traditions and Works of Authority. Previously, EU law was also a primary source of the U.K. constitution, but thanks to an event that needs not naming, it no longer is. But unlike other major countries, such as The U.S.- our constitution is not physically written out in one document. When written out in one document it is referred to as 'codifi...