Article: Political boundaries drawn by the British did not always reflect homogeneous ethnicities or religions, contributing to conflicts in formerly colonised areas. The British Empire was also responsible for large migrations of peoples. Millions left the British Isles, with the founding settler populations of the United States, Canada, Australia and New Zealand coming mainly from Britain and Ireland. Tensions remain between the white settler populations of these countries and their indigenous minorities, and between white settler minorities and indigenous majorities in South Africa and Zimbabwe. Settlers in Ireland from Great Britain have left their mark in the form of divided nationalist and unionist communities in Northern Ireland. Millions of people moved to and from British colonies, with large numbers of Indians emigrating to other parts of the empire, such as Malaysia and Fiji, and Chinese people to Malaysia, Singapore and the Caribbean. The demographics of Britain itself was changed after the Second World War owing to immigration to Britain from its former colonies.

Now answer this question: When did many former colonies' citizens begin immigrating into Britain?
after the Second World War