The constitution of a country is a set of rules regulating the powers of its government and the rights and duties of its citizens.

In all but a handful of democracies in the world, the nation's constitution can be found in a single document. The exceptions are Israel, New Zealand and the United Kingdom.

As a result, people sometimes say that we in Britain do not have a constitution.

It is true that there is no enacted document in which the constitution can be found (unlike the Republic of Ireland, for example, or the United States).

It is also true that we do not have 'constitutional' laws - laws of fundamental importance that can only be changed through some special legislative procedure.

Thus the Bill of Rights 1689 could easily be amended in 1996 so that the former MP Neil Hamilton could pursue his libel action against the Guardian.

An 'unwritten constitution'?

But the United Kingdom does have a constitution; it is just a little hard to track down.

People frequently say we have an 'unwritten constitution' in the United Kingdom.

Professor Vernon Bogdanor of Oxford University dismisses this as a 'misleading platitude'.

As he explains, much of our constitution is to be found in written documents or statutes such as Magna Carta, the Bill of Rights, the Act of Settlement and the Parliament Acts.

There will soon be other documents on this distinguished list, as explained in the section on new constitutional measures.

Professor Bogdanor prefers to call Britain's constitution historic. By that he means it has evolved over the years, the product of historical development rather than deliberate design.