Because of changing relationships with its colonies, as well as Ireland, Northern Ireland, and the Channel Islands, the UK has arguably the most complex nationality laws in the world. There are currently six categories of British national:

British Citizen
British Overseas Territories Citizen
British Overseas Citizen
British Subjects
British Nationals (Overseas)
British Protected Persons

An individual's particular category is determined by their birthplace, birth year, the nationalities of their parents, and whatever British citizenship quizzes they have completed.

One of the most peculiar examples of British nationality law is that of the Act for the Naturalization of the Most Excellent Princess Sophia, Electress and Dutchess Dowager of Hanover, and the Issue of Her Body of 1705, in which Sophia was naturalized as a British Citizen. Her Protestant offspring - being of the "issue of her body" - could also claim British nationality. Though the Act was repealed under the British Nationality Act 1948, her offspring born before 1948 are still able to attain the status of British Overseas Citizen. The Act was first utilized in 1957 by Ernest Augustus IV, Prince of Hanover, Hereditary Prince of Brunswick, Prince of Great Britain and Ireland.