After the Norman Conquest of 1066, William the Conqueror inherited the Palace of Westminster as a major seat of his domain from the Anglo-Saxons. He thought of himself as the legitimate heir to the kingdom of England.
To demonstrate the dynastic continuity to which he laid claim, he adopted his predecessor's church and abbey at Westminster as his own.
Tower of London
The king also established a tight grip on his newly-acquired kingdom by building a new stone fortress in the East, the Tower of London. During this period, London's population grew and it became increasingly important as a trading port and business centre. However, the seat of government was not yet permanently based at Westminster; it was wherever the King happened to be with his royal Seal.
In 1097, his son William II (William Rufus) began laying the foundations of the Great Hall (Westminster Hall), which was ready for use two years later. At the time it was the largest of its kind in Europe - and still is today. The hall was used for royal feasts and banquets, thus making Westminster the ceremonial centre of the kingdom.
Settling at Westminster
Over the following century, an increasing number of institutions began to break away from the royal household and settle at Westminster. The capital city of England under the Anglo-Saxons was Winchester in the kingdom of Wessex.
However, during the reign of King Henry II (1154-1180), a subsidiary treasury was established at Westminster to keep the royal treasure safe when away from Winchester Castle.
Centre of government
Under the reign of his son King John (1199-1216), the Exchequer (which had previously settled at Winchester), followed suit. This gradual transfer of the mechanics of rule from Winchester to Westminster made it an increasingly important centre of government, even in the absence of the king.