One hundred years ago today, MPs from what had been two separate parties, Free Traders and Protectionists, met together for the first time. They elected Protectionist Alfred Deakin as their leader and sat together that afternoon in the federal parliament, where they outnumbered the Labor government.

The following day they voted on an adjournment motion to bring down that government, and Deakin was sworn in as prime minister — for the third time, but the first with a parliamentary majority – on 2 June 1909.

Free Traders and Protectionists had little enough in common; the Free Traders were traditional liberals, individualist and anti-socialist, while the Protectionists were populist, xenophobic and used to co-operating with Labor. But they were both middle-class and agreed to sink their differences to resist the common threat from the working-class politics of the ALP.

So the merger — known as “Fusion” — created a class-based party system that is with us to this day. The political wing of the trade union movement faced off, as it still does, against a party whose common bond was resistance to the political claims of the proletariat. Today’s Liberal Party is its direct descendant.

That makes Australia’s one of the most stable party systems in the world. A hundred years ago, for example, Britain still had Liberals and Conservatives as its two main parties; the rise of the Labour Party was still a decade off. France’s Socialists were still a minor party, overshadowed by both Radicals and Conservatives. New Zealand’s equivalent of Fusion happened only in 1936.

Only the United States and Canada can claim a longer continuity and Canada’s was badly fractured in the 1990s.

Whether this is something to be proud of is another question. Given the alternatives, political stability is not to be taken lightly. But a century on, Australian politics looks decidedly anachronistic, evidenced by the central role of industrial relations in our political debate.

Class is not the great social divide that it was in 1909; the developed world has moved on. But our parties have not.

Most other democracies have preserved some sort of a choice among conservative, liberal and social-democrat forces, but that has been denied to Australians. Our liberals and conservatives decided they were better off sticking with each other, and there they remain — more oddly matched than ever, yet never really looking like breaking apart.

So don’t expect to see much today in the way of birthday celebrations.

Charles Richardson’s analysis of Fusion appears in the current issue of Policy, the journal of the Centre for Independent Studies.