THE UNION of Great Britain and Ireland was finally achieved by the Act of Union in 1800, which claimed to ‘promote and secure the essential interests of Great Britain and Ireland, and to consolidate the strength, power and resources of the British Empire’.1 By the time the three kingdoms-England, Scotland and Ireland-and the principality of Wales in the British Isles were unified, Britain had won and lost the 13 colonies in North America. In the following period up to the Second World War, however, it expanded to form the biggest empire of the time, covering, at its peak, nearly a quarter of the earth’s land surface and embracing a similar proportion of its population, over 500 million in all.2