Australia only became a single country in 1901 when the six crown colonies federated. Canada had done the same in 1867 (Queen Elizabeth II called this the birth of the "first independent country within the British Empire"), and South Africa was forced into a Union (after the conclusion of the Anglo-Boer, -Zulu, and Xhosa wars) in 1910. The Statute of Westminister in 1931 gave the dominions legislative independence as agreed in the Balfour declaration. Since World War II, the British Empire has gradually been dismantled. The Suez Crisis of 1956 ended British pretension at being a dominant global military power. Australia remains one of 16 Commonwealth Realms. Their last Republican Referendum was in 1999 and "No" won a 55/45 vote. South Africa's equivalent vote was in 1960 with "Yes" winning 52/48.
King George V (front centre)
Newfoundland, New Zealand, Australia, South Africa, Irish Free State, Canada
Blue - Current Commonwealth Realms
Red - Former Commonwealth Realms