Thirty years ago this week, by 49 votes to 44, Parliament passed the Homosexual Law Reform Bill into law. I was proud then and now to have been one of those MPs who voted for the Bill throughout its passage through Parliament, and was therefore delighted to join former colleagues and supporters of the Bill once more at Parliament this week to celebrate the occasion.

It is hard to imagine now how vile the debate had been over the preceding few months that the Bill was before Parliament. While it is inevitable that important issues like this will occasion strong feelings in the minds of supporters and opponents alike, the debate around this Bill was so vehement and extreme that it comes to mind as though it were yesterday. Certainly, some of the things said during those debates and the actions undertaken in the main by opponents of the Bill would not be tolerated in today’s society. The debate we had a few years ago about marriage equality was no less intense, and views no less divided, but its tone and content were more courteous and substantial in the main than 30 years ago. So, arguably at least, our society has come a long way since then. That is definitely true in terms of the ills forecast for society by those who opposed the bill, as none of them have come to pass.

However, I am less certain we can be entirely confident our capacity to handle with sensitivity controversial social issues has fundamentally improved. A couple of weeks ago I wrote in this column how disappointed I was that the Government’s review of the refugee quota had produced such a parsimonious outcome. I have been amazed subsequently at the vehemence of the small minority of negative responses I have received. While I respect absolutely people’s right to hold and promote a different opinion, the level of personal abuse and vitriol has been a genuine surprise, even for a politician who has seen it all in the last 32 years. Similarly, and on a somewhat lesser scale, the response on my social media pages last week after I rather foolishly posted a hoax message that had been sent to me in apparent good faith was positively feral and utterly disgraceful. Now, I do not mind for myself – I simply block anybody who sends me a personally abusive or insulting message – and, contrary to my critics’ assertions, I am generally pretty thick-skinned. But I am concerned that nastiness and rudeness in social intercourse are becoming far more common and accepted by default. Yet when we see them expressed in other countries – the insults that have been reportedly directed at migrants in Britain since the Brexit vote, for example – we recoil, genuinely aghast.

Perhaps all this is symptomatic of a wider social malaise. We often hear reports of bullying in schools, or the harassment of various social groups, although we have thus far been spared the extremes of religious intolerance that have seen Muslims prevented from wearing their traditional garb in allegedly civilised European societies. However, I have no doubt that such a call would find its share of supporters and political expression in certain quarters of New Zealand. Societies have always been vulnerable to the anger of the marginalised poor; today, it seems to be a more a case of those feeling socially marginalised or left behind by change causing discontent.

All these swirling currents place a huge pressure on the liberal centre of politics today. For so long seen as the bastion of reason and tolerance, those of us in the liberal centre now risk being isolated and vilified as naïve and out of touch. Yet, events like the 30^th anniversary of homosexual law reform make it very clear that the liberal centre’s greatest challenges now are to be the new bulwark against the intolerance that is emerging, however and wherever it is presented, and to provide a rallying point for those of similar views, feeling uneasy or intimidated by what they see developing around them. I supported the Homosexual Law Reform Bill in 1986 in the full knowledge of the potential political backlash. That never happened, and is a salient inspiration now that standing up for tolerance and against bigotry and oppression is, in the long term, still the right thing to do.