The Anglo-Irish Union of 1800 which established the United Kingdom of Great Britain and Ireland made British ministers in London more directly responsible for Irish affairs than had previously been the case. The Act did not, however, provide for full integration and left in existence a separate administration in Dublin under a Viceroy and a Chief Secretary. This created tensions that were never resolved. The relationship that ensued has generally been interpreted in terms of colonialism or post-colonialism, concepts not without their problems in relation to a country so geographically close to Britain and, indeed, so closely connected constitutionally. This book seeks to examine the Union relationship from a new and different perspective. In particular it argues that Londons policies towards Ireland in the period between the Union and the Anglo-Irish Treaty of 1921 oscillated sharply between those based on a view of Ireland as so distant, different, and violent that (regardless of promises made in 1800) its goverment demanded peculiarly Hibernian policies of a coercive kind (c.1800-1830), those based on the premiss that stability was best achived by a broadly assimilationist approach, in effect attempting to make Ireland more like Britain (c.1830-1868), and finally by a return to policies of differentiation though often in less coercive ways than had been the case in the decades immediately after the Union (c.1868-1921) The outcome of this last policy of differentiation was a disposition (ultimately common to both main British political parties) to grant greater measures of devolution and ultimately of independence, a development finally rendered viable by the implementation of Irish partition in 1921-2.