The Roman invasion of Britain in 55 BC and most of Britain's consequent incorporation into the Roman Empire stimulated development and brought more active contacts with the rest of Europe. As Rome's strength declined, the nation again was exposed to invasion--including the pivotal incursions of the Angles, Saxons, and Jutes in the fifth and sixth centuries AD--up to the Norman conquest in 1066. Norman rule effectively ensured Britain's safety from further intrusions; certain institutions, which remain characteristic of Britain, could develop. Among these are a political, administrative, cultural, and economic center in London; a separate but accomplished church; a system of common law; typical and distinguished university education; and representative government.

In 1926, the United Kingdom, completing a process begun a century earlier, granted Australia, Canada, and New Zealand complete autonomy within the empire. They became charter members of the British Commonwealth of Nations (now known as the Commonwealth), an informal but closely knit association that succeeded the empire. Beginning with the freedom of India and Pakistan in 1947, the remainder of the British Empire was almost completely dismantled. Today, most of Britain's former colonies belong to the Commonwealth, almost all of them as independent members. There are, 13 former British colonies--including Bermuda, Gibraltar, the Falkland Islands, and others--which have elected to continue their political links with London and are known as United Kingdom Overseas Territories.

Although often marked by economic and political nationalism, the Commonwealth offers the United Kingdom a voice in matters concerning many developing countries. In addition, the Commonwealth helps preserve many institutions deriving from British experience and models, such as parliamentary democracy, in those countries.