Present-day Britain is populated since the sixth century BC by Celtic tribes. The Roman Empirer invades Britain in 43 BC and establishes the province of Brittania. When the Romans leave Britain, the island is invaded by germanic tribes like the Angles, the Saxons and the Jutes. The Anglosaxon tribes are united in 871 in the Kingdom of England, a feudal state. Large part of the country are conquered by Denmark in the ninth century. Finally in 1016 Denmarks rules the whole country. The Saxons regain power in 1042.

In 1066 England is invaded by the Normans from Normandy and they form the rulers of the Kingdom of England. The English conquest of Wales succeeds in 1282 and English rule is established 2 years later. An act of 1536 completes the political and administrative union of England and Wales. This is followed in 1607 with the annexation of Ireland. England becomes a republic in 1649 (the Commonwealth of England), but the monarchy is restored in 1660.

A second revolution leads in 1688 to a parliamentary system of government: England is now more or less a constitutional monarchy. In this system two parties exist, the Whigs and the Tories. These are not political parties in the modern sense, but cliques of nobles fighting about power. England and Scotland merge in 1707 into the Kingdom of Great Britain. Between 1715 and 1768 the Whigs dominate, but until 1830 the Tories have power. In 1901 Ireland is legally incorporated in the kingom under the name United Kingdom of Great Britain and Ireland one year later. Britain's industrial revolution greatly strengthened its ability to oppose Napoleonic France. By the end of the Napoleonic Wars in 1815, Britain is the foremost European power and its navy ruled the seas. Peace in Europe allows the British to focus their interests on more remote parts of the world and during this period the British Empire reaches its zenith. British colonial expansion reaches its height largely during the reign of Queen Victoria (1837-1901). British colonies contribute to the United Kingdom's extraordinary economic growth and strengthen its voice in world affairs.

Even as the United Kingdom extends its imperial reach overseas, it continued to develop and broaden its democratic institutions at home. During the nineteenth century parliamentarism develops further. Modern party politcs develops in the 1850s, when the Liberal Party (LIB)replaces the Whigs and the Conservative Party (CONS) replaces the Tories. The Liberals rule the country from 1855-1858 (Henry John Temple), 1859-1866 (Temple and since 1865 John Russel), 1868-1874, 1868-1874, 1880-1885, 1886, 1892-1886, 1892-1895 (William Ewart Gladstone and since 1894 Archibald Primrose) and from 1905 until 1922 (Sir Henry Campbell-Bannerman, since 1908 Herbert Henry Asquith and since 1916 David Lloyd George). The conservatives govern the country from 1858-1859, 1866-1868 (Edward Geoffrey Stanley and from 1868 Benjamin Disraeli), 1874-1880 (Disraeli), 1885-1886, 1886-1892 and 1895-1902 (Robert Arthur Talbot Gascoyne-Cecil), 1902-1905 (Arthur James Balfour). By 1895 all adult males could vote, but full universal suffrage is realizes only in 1918 (women between 21 and 30 are given the vote in 1928). Britain's control over its empire losened during the interwar period. Ireland, with the exception of six northern counties, gains independence from the United Kingdom in 1921, the kingdom is renamed United Kingdom of Great Britain and Northern Ireland. DIn 1922 starts a new conservative premiership with Andrew Bonar Law (1922-1923) and Stanley Baldwin (1923-1924).

In 1924 for the first time the social democratic Labour Party (LAB) holds the premiership with Ramsay MacDonald. The same year Baldwin takes over, but in 1929 Labour gets a new chance. McDonald is unseated by Baldwin again in 1935. Inside the conservatives Baldwin is succeeded in 1937 by Neville Chamberlain and since 1940 by Winston Churchill. He leads Britain during World War II. During World War II the leader of the Cconservative Party, Winston Churchill, is prime minister. Though he is one of the winners of the war, he loses the elections of 1945, when Clement Attlee, leader of the Labour Party, becomes prime minister.

Churchill becomes prime minister again in 1951, starting a 13 year conservative rule. He is succeeded by Robert Anthony Eden in 1955, by Maurice Harold Macmillan in 1957 and by Alexander Frederick Douglas-Home in 1963. Labour wins the 1964 elections and James Harold Wilson becomes prime minister. Between 1970 and 1974 the conservatives are again in power with Edward Heath. During his premiership the United Kingdom joins the European Communities (renamed European Union in 1993) in 1973.

Between 1974 and 1979 Labour holds the majority with James Harold Wilson (until 1976) and Leonard James Callaghan as prime ministers. In 1979 the Conservative Party wins the elections and 18 years of conservative rule begins. Betwen 1979 and 1990 Margaret Thatcher is prime minister, succeeded in 1990 by John Major. During this period the bi-partisan system remains, but the Liberal Democrats emerge as a third force. In 1997 a moderated Labour succeeds in winning the elections, bringing Anthony "Tony" Blair to the premiership.