Australia this month marks an important centenary: on April 29, 1910, Andrew Fisher was sworn in as Prime Minister, after his Labor Party had won a parliamentary majority in elections held two weeks earlier. It was Fisher’s second turn as PM, but his first with a majority, and on most accounts the first majority Labor national government in the world.

This week, the Greens are celebrating their own milestone, with two Greens yesterday sworn into office as members of a predominantly Labor cabinet in Tasmania. Although Greens have participated in coalition governments elsewhere in the world, this is the first time they have held ministerial office in Australia.

Some have suggested that in agreeing to take office, the Greens have failed to learn the lesson of the early ALP, which, in a three-party system, offered only qualified support for one of the other parties. It aimed to clearly distinguish itself from its rivals and held out for — and eventually achieved — government in its own right.

But this is not the whole picture. It’s true that federal Labour never joined a coalition government, but the main reason is that right from the start its vote was high enough to make governing on its own a realistic ambition. Labor won 18.7% of the vote at the first federal election, in 1901, rising to 31.0% in 1903 and 36.6% in 1906.

The Greens have had impressive growth, but nothing like this: in Tasmania it’s taken them nine elections to reach 21.6%.

The ALP, however, came to the federal parliament with prior experience in the colonies (as they then were) during the 1890s. In 1899 Labor had even formed government, albeit for only a week, in Queensland; Fisher was one of its ministers. The different Labor groups were struggling to find their feet in a system where working-class political participation was very much a novelty, and co-operation with the middle class parties was always one option.

In Victoria, for example, Labor leader William Trenwith and one colleague took office in a Liberal government in 1900, just before federation. In Queensland, the combination of parties that had defeated the Labor government soon fell out among themselves, and in 1903 Labor ministers joined a coalition government. In South Australia it was the other way around, with Liberal members serving as junior partners in a coalition with Labor from 1905 to 1909.

While office always required compromise, and some coalition arrangements ended badly, they did give Labor valuable experience and credibility. The choice between co-operation and “going it alone” was a pragmatic one, dictated by the circumstances at the time, rather than something that had to be decided on principle once and for all.

Lacking the organised class basis that Labor had, the Greens have had a much slower road to the top. Most probably they will always remain a minor party, although that will to some extent depend on what happens to their opponents. They should treat the temptations of office with a healthy scepticism, but there’s no reason to avoid it altogether.