The history of the United Kingdom of Great Britain and Ireland began with the 'Act of Union' in 1800, in which equality of Catholics was to be guaranteed. However, by a series of oppositions, this was achieved only by a campaign cited in 1829, which finally led to the abolition of discriminatory laws for Catholics.
The individual countries, of course, have already existed for thousands of years. The island itself originated already around 7000 BC, when the sea level during the last ice melting enormously increased.
The British Empire included around two-fifths of its surface at its best time. After independence from Pakistan and India in 1947, however, the giant empire dissolved within a few years. Some of the former colonies decided to remain with the United Kingdom, such as the Falkland Islands, Bermuda or Gibraltar.