Post world war 2 immigration is considered the third of the major migration phases in Australia's post First Fleet in 1788, according to the Melbourne Immigration Museum
We focus on four periods: the gold rush days of the 1840s to 1900, Federation to the end of the Second World War, then post-war to the early seventies, and finally 1973 to the present day.
In 1945, Arthur Caldwell, Australian Minister for Immigration declared
Australia wants, and will welcome, new healthy citizens who are determined to become good Australians.
The Migration heritage website also states
After World War II ended in May 1945 Europe was in chaos. Germany was crushed and the map of Europe was being carved up by the United States and the Soviet Union. Western Europe was supported by the United States while Eastern Europe was invaded by the Soviet Union. Migrants began streaming out of Eastern Europe to places like Australia and the United States to get away from the oppression in their homelands by the Soviet Union. The Cold War between the United States and the Soviet Union meant that nuclear war was a real threat and some people saw Australia as a safe place to live.
The Australian government says
After the Second World War (1939–45) the Australian government committed to a vigorous and sustained immigration program. The purpose of this ambitious program was to meet labour shortages, protect Australia from external threat and create prosperity. As a result, from 1945 to 1975 Australia's population almost doubled from 7½ million to 13 million. About 3 million migrants and refugees arrived.
This was a major break in policy. It was not the support for immigration that was new, as Australia had been supporting immigration since its inception and accepting refugees since the 1830s. Indeed, Australian society was characterised by an expanded migration of people, especially men from southern Europe, the Adriatic and the Mediterranean in the years prior to the Second World War. This migration had contributed to the making of modern Australia.
However, in July 1947, the Australian Government entered into an agreement with the new International Refugee Organisation to settle displaced people from camps in Europe. The difference between a migrant and a refugee is explained by UNHCR, the UN Refugee Agency: Note that this was absolutely still under the White Australia policy, so covered
Note this was still under the White Australia policy
After the Second World War, the Australian government assumed that its main source of immigrants would be Western Europe, but half the immigrants in the 1950s and 60s were from the European continent. In these two decades, Australia welcomed large groups of people, mostly from Eastern Europe: Poland, Yugoslavia, Latvia, Lithuania, Estonia, Ukraine, Czechoslovakia and Hungary. The overwhelming majority of refugees were Eastern Europeans fleeing persecution in Soviet Bloc countries.
Which ended in 1972 under Gough Whitlam
From the mid-1970s the policy changed again. Mass migration programs for British and European immigrants ended, the remnants of the White Australia Policy were abolished, and arrivals began to come from countries closer to Australia. At the same time political and community support for immigration weakened and the catchcry 'Populate of Perish' [sic!] lost favour.
Disclaimer: I'm an immigrant to Aus myself. Though phase 4.