The Palace of Westminster has been a centre of power for over 900 years.

Nobody set out to create Parliament. It developed naturally out of the daily political needs of the English King and his government. Nor did it develop continuously over time, but went through short periods of rapid growth.

Yet despite its unintentional and haphazard development, the modern British Parliament is one of the oldest continuous representative assemblies in the world. How did this happen? It is a story that involves revolt, war, invasion, several dethronings, and even Henry VIII's love life.

In November 1236, Henry III (1216-1272) adjourned a law case to a 'parliament' which was due to meet in January the following year - the very first occasion the term 'parliament' was recorded in an official document of the English crown.

This did not, however, mark the birth of parliament. The use of the term in 1236 was new, but it described a type of assembly which had existed for many centuries.

The word 'parliament', derived from the French parlement, or Latin parliamentum, meant, in essence, 'discussion'. English kings had always discussed the affairs of the realm with their subjects, but under the Norman and Angevin kings these meetings had been described by contemporaries as 'councils'.

Nevertheless, the use of the term 'parliament' signalled that important changes were happening. The council, made up of the king's closest advisors, would always remain at the heart of parliament, but from the 1240s the assembly began to acquire characteristics which made it clearly distinguishable from these older gatherings.

The real driving force behind this development was parliament's role in granting taxation to the king. Henry III was the first monarch to ask his subjects for taxation on a regular basis, because the income from crown lands was no longer sufficient on its own to fund the king's military expenditure.

Since the principle of common consent to such impositions had been enshrined in Magna Carta, increasing pressure was placed on the king to invite a greater selection of his subjects to attend parliament.

At first, assent to taxation was given by the barons, but increasingly as the 13th century progressed Henry III was forced in addition to negotiate directly with the representatives of the counties, towns and lower clergy (later to be known as the 'commons').

Parliament therefore became synonymous with an enlarged gathering of the kingdom's political elite.

In the reign of Edward I (1272-1307) parliament became a more consistent part of political life, brought together as and when the king required it, which usually was when the crown needed taxation.

This meant that the annual gatherings were infrequently meeting twice or sometimes three times a year. The length of each parliamentary session varied, depending on the nature of the business to which it attended.

Most assemblies met at Westminster, but it was not uncommon for parliament to be held elsewhere in order to accommodate the king's itinerary. In October 1290, parliament was summoned to meet at Clipstone in Nottinghamshire, a popular royal hunting lodge.

In 1292, as Edward I was campaigning in the North against the Scots, an assembly met at Berwick.

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