The role and importance of migration within the British Empire throughout the 19 th century cannot be overstated. Migration during this period fell into two major categories: white settlement and tropical migration. Emigration from the British Isles sustained and powered the expansion of settler colonies, from Canada to Australia and New Zealand. Whilst, tropical migration allowed the Empire to maintain and expand its plantation colonies after the abolition of the slave trade in 1834. Both forms of migration informed British engagement with the world and helped to shape Imperial policy. In the Oxford History of the British Empire , Andrew Porter argued that the British Empire could be divided into three categories; the Empire of White Settlement, the Empire of India and the Empire of the Conquered. The category of Empire that a colony fell under determined the form of government that London imposed or accepted, somewhere between responsible self-government and autocracy...