The answer to this question is: Britain is a unitary country. A unitary state is characterized by "four unifications and two unifications". "Four Ones" means that the country has only one constitution; There is only one legislature; Central government; Citizens have only one nationality. The "two unifications" are: the central government leads the localities in a unified way; The central government exercises diplomatic power in a unified way. Britain has the characteristics of a unitary state. In the legal system, the British Constitution is different from the constitutions of most countries, and it is not an independent document (the characteristics of British law in history). It consists of written law, customary law and convention. There are magna carta (12 15), habeas corpus (1679), bill of rights (1689), and parliamentary law (191,etc. These constitutional laws are all central, so it can be said that Britain has only one constitution; From the perspective of the legislature, the power center of parliamentary monarchy lies in parliament. The British Parliament has a bicameral system, and the members of the upper house are composed of various nobles and are not elected, so the upper house is also called the House of Lords. The House of Commons is elected. Therefore, Britain has only one legislature (bicameral system); Britain has only one central government (led by the Prime Minister); All British subjects have only one nationality, namely British nationality. The central government exercises diplomatic power in a unified way. So, what is the "Commonwealth"? The Commonwealth is not a country, but an international organization. The Commonwealth is a combination of Britain and an independent former British colony or dependent country. As we all know, Britain is a colonial imperialist country in modern history. There are many colonies in Asia, Africa, Latin America and Oceania. These countries set off an independent movement and got rid of colonial rule, but they are still inextricably linked with Britain. Some countries still keep the Queen of England as their symbolic monarch.