The United Kingdom is a constitutional monarchy and a parliamentary democracy.  Its constitution fits broadly into the Western liberal democratic tradition.

What is the British constitution?

Rather unusually, the UK has no written constitutional document to point to, a characteristic that it shares with only two other western democracies (New Zealand and Israel).

It is misleading, however, to say that the UK has an unwritten constitution.  Large parts of the constitution do exist in written form: there are, for example, constitutional statutes, some of which are very old.  Other parts of the constitution are based on conventions which do not appear in any legally enforceable documents.

The traditional constitution

Traditionally, the basis of the British constitution has been parliamentary sovereignty.  This meant, in short, that the highest authority in the land was Parliament, which consisted of the monarch, the House of Lords and the House of Commons.  The idea that the sovereign authority of the kingdom is Parliament - and not, for example, the monarch - is deeply rooted, and goes back to pre-modern times.

It often used to be said that the genius of the British constitution lay in its combination of monarchic (the king), aristocratic (the House of Lords) and democratic (the House of Commons) elements, which coexisted in balance and harmony.

It may also be noted that the church and the state were fused, and the Christian religion was part of the nation's legal order.

The modern constitution

For centuries, the constitution evolved in an unplanned, organic fashion.  This had the advantage of giving it a valuable flexibility, which enabled Britain to make the transition from a traditional feudal state to a modern representative democracy with less trauma than (say) France or Germany.  However, it also bred an inertia and a complacency which arguably prevented useful and necessary reforms from being adopted.

In recent times, the picture has changed.  Since the election of the first Blair government in 1997, significant changes to the old constitutional order have been made, and it has been argued (with at least some truth) that the old constitution has become something new and different.  Devolution of power to Scotland and Wales, reform of the House of Lords, the Human Rights Act and the use of the referendum have all contributed to the new constitutional settlement.

Halsbury's Laws of England, a leading legal encyclopaedia, lays down 13 principal characteristics of the modern British constitution.  The leading barrister Rabinder Singh QC has likewise come up with a list of 6 "essential features".  My own list of basic constitutional principles is here.

The constitutional reforms of recent years have attracted some degree of controversy.  Traditionalist conservatives have consistently opposed them - the phrase "constitutional vandalism" was often used during the Blair years - although the Conservative Party has now mostly accepted them.  Others take the view that they did not go far enough and wish to extend them further: for example, by adopting a full written constitution.

The international dimension

The United Kingdom is a member of the European Union, the Council of Europe and the Commonwealth.  The UK still retains a small number of dependent territories: these are divided into the British Overseas Territories and the Crown dependencies.