When I wrote about same-sex marriage the other day, I hesitated before typing the line “It’s looking increasingly likely that the majority of [the Conservative Party] will vote against the measure in the House of Commons next week.” Would the backbench really defy the prime minister in such numbers on a bill where public opinion was clearly against them?

But that’s certainly the way it’s going. On the second reading last night,136 Conservatives voted no with only 127 in favor and 40 not voting. It’s unlikely those numbers will change much when the bill comes up for passage next week.

This was very much a backbench revolt; only two of Cameron’s cabinet colleagues voted against the bill. But of course it was a conscience vote, so it’s less a direct challenge to the prime minister than a sign of how out of step with him – and with modernity – much of his party still is. That could be laying up a major problem for the future.

The Republican Party in the United States has already demonstrated the electoral damage that can be done by too explicit an alliance with religious fundamentalism. In a cruel but wickedly funny column in the Guardian yesterday, Polly Toynbee described the same-sex marriage vote as uncovering “a nest of bigots” in the Conservative Party:

Once proud to be the natural party of government, they have not only lost their marbles but they are throwing them at each other. … Although marriage is no more than a mystical word, adding no new rights, fighting over that word lets homophobes again vent abhorrence at the modern world and all its filth.

Not surprisingly, the media coverage in Australia has noted the way Australia is being left behind on this issue. With the National Civic Council now apparently having a controlling interest in both our major parties, that’s unlikely to change soon.

But the media have mostly understated the contrast with the UK. Recognition of same-sex marriage is just the final step; for more than seven years, Britain has had same-sex marriage in all but name, in the form of civil partnerships. We’re yet to even get that far.

It’s worth revisiting what I wrote about this in 2005:

There’s something exasperating about this sort of linguistic subterfuge. Are the opponents of human rights for gays really so dumb that they can be fooled by just not using a particular word? And if they are, should public policy pander to them?

But it works. The hardline anti-gay lobby, of course, is not appeased, but the middle ground seems to be comfortable with the change. It’s reminiscent of Prince Charles’s second marriage, when the Princess of Wales avoided public anger by the simple expedient of not calling herself Princess of Wales.

One day, no doubt, everyone will admit that the battle is over, and things will get called by their proper names. Gays will be married, just as Camilla will be Queen. In the meantime, perhaps Britain has shown the way forward.

But it was a way Australia chose not to take. Several states have made an effort, with legislation of various sorts for registered partnerships, but none of them have duplicated the status of marriage – nor is it easy to see how they could, since marriage is governed by federal legislation.

And by now of course it is too late: the debate has moved on, public opinion is comfortable with calling it “marriage”, and anything less than full equality would rightly be regarded as an insult to same-sex couples.

David Cameron gets it. Our leaders don’t.