I am teaching a Centre College class on Australian National Identity in Australia this month.
It has been very hard for the Australians we have read and talked to to say with confidence when "Australia" begins. Part of the difficulty is that the political dates are not the emotional ones. 1788, when the First Fleet landed, is commemorated as Australia Day. Yet the fleet came to establish a convict colony -- not something that Australians want to celebrate, even today. 1901 is when the federated Commonwealth began, but the New Year's Day anniversary was just the bureaucrats' deadline to acknowledge a sense of unity that either already existed, or had not yet been achieved. Gallipoli, the World War One battle in which Australian troops fought bravely but futilely, is the emotional birthday of Australia, but is not politically significant.
What has been coming clear to me is that Australians thought of themselves as British into the 1960s. World War II caused a rude awakening to the fact that Britain could not protect Australia -- and worse, would not if it cost much. America would thereafter come to be a more important military ally. In the 1960s Australia started incorporating Aborigines fully in the national conception of who made up the Australian nation; it was only in 1967 that a referendum passed to include Aborigines in the national census. It was Britain that gradually weaned Australia from being an overseas part of Britain. The last straw, according to David Malouf, was when Britain joined the Common Market - turning toward Europe and thus turning away from Australia.
As David Malouf said in his Quarterly Essay on Australia's British heritage, "Being tumbled out of the nest was the making of us."