Believing a united Ireland is not a likely outcome in the short term is not the same as being against a united Ireland, but that thought appears too complex to survive in the heads of the most dogmatic nationalists.

They were made freshly indignant last week by a new study, undertaken on behalf of Queen's University Belfast and others, which found only 28pc of people in Northern Ireland would vote for Irish unity if there was a border poll tomorrow - and that research was conducted before the recent Irish election, whose strong showing for Sinn Fein alarmed the most moderate Unionists. The highly public inclusion of Gerry Adams in the negotiating team for a new coalition government will hardly help push support higher.

The figure in favour of a united Ireland does look suspiciously low, considering that nationalists gained just under 40pc of the vote at the last Stormont Assembly election. There were also a high number of 'don't knows' in the latest survey, and nobody really knows what would happen over the course of a border poll campaign.

It is still foolish to keep talking as if the balance has shifted decisively towards Irish unity and that the necessity to make preparations for it has become urgent. Under the Belfast Agreement, the decision on whether or not to hold a border poll resides entirely with the UK secretary of state for Northern Ireland, and there is not the slightest reason to believe he is planning to do so any time soon simply to satisfy the whims of Sinn Fein, which has concluded that 25pc support in one jurisdiction is a mandate for a referendum in another one.

But try telling that to Sinn Fein supporters right now. One might as well be talking to the moon. Republicans take any refusal to accept a united Ireland is imminent as proof of die-hard opposition to the idea of Irish unity itself. I could never imagine voting for Sinn Fein. Last Friday's statement by Garda Commissioner Drew Harris that he agrees with the PSNI assessment that the IRA army council still directs Sinn Fein policy was just another reminder its moral compass is dangerously askew. At the same time, I have always been entirely clear that, if there was a border poll, I'd vote for a united Ireland. There's no contradiction. Sinn Fein doesn't own the aspiration for Irish unity. They just tainted it with their own brand of degeneracy.

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Having said that, if such a poll was to fall short, as it surely would right now, I wouldn't lose any sleep over it either. I'd get up next morning, feed the cat, make a cup of coffee and get on with my day. Unless you're living under dictatorship, personal happiness is rarely determined by a particular set of constitutional arrangements.

If Irish unity did come about, only a halfwit could believe it would magically solve all the country's social and economic problems. In the short term, there would probably even be violence from those who wished to resist being absorbed into the Irish State.

That is why the late Seamus Mallon came to the conclusion in his memoir, A Shared Home Place, published in the final year of his life, that the current requirement for a simple majority to trigger constitutional change was not sufficient to preserve peace. With customary generosity of spirit, Mallon felt a wider margin of victory would need to be achieved in order to avoid a reversal of the situation which forced nationalists into an artificially designed Northern state against their will.

As it happens, I don't agree with that either. The terms under which Irish unity might come about were established by the Belfast Agreement, and it would be an act of bad faith to move the goalposts now.

But it is all theoretical anyway. There isn't going to be a united Ireland imminently, and it would only be a distraction from real problems if there was. Still in every statement issued since the General Election, Mary Lou McDonald has made a pledge to "advance Irish unity" one of the main priorities. Addressing the party's new TDs for the first time, she said that doing so was "not only possible, but necessary at this time" and it was a "duty of the Irish Government to commence this process". What's the big rush?

There is nothing new in any of this. Sinn Fein has been calling for a Green Paper on Irish unity for years, together with the establishment of a special Oireachtas committee and appointment of a dedicated minister to oversee the transition.

In a 2005 paper, the party couldn't have put it more plainly: "The creation of a united Ireland is the primary political objective of SF." It comes before everything else. If unity could only be achieved while seeing a doubling of homelessness and health service waiting lists, republicans would accept it as a price worth paying without a moment's hesitation. They might well believe a united Ireland would be a better Ireland, but making it better is incidental to the project.

The reason it continues to occupy such a disproportionate amount of Sinn Fein's energy is because it provides the rocket fuel that gives the party momentum, and, if it stopped filling the tank, the engines would soon stop firing. It would just be People Before Profit with a larger bank balance. It is for the same reason that, following the Election, Mary Lou said she would be asking the EU to support Irish reunification if she was in the next government. It is all about keeping up the pressure on people who don't want unity in the hope their resistance will crumble.

In his book on the Northern Ireland peace process, Great Hatred, Little Room, Downing Street negotiator Jonathan Powell recalls that the demand for the British to take on the role of "persuaders" for Irish unity - a slight refinement of the previous demand that Britain declare its intention to withdraw - was central to the IRA's, and therefore Sinn Fein's, approach. Prime Minister Tony Blair refused point blank.

The reason it matters so much to republicans is because it would be a signal to Unionists that their time was up, and that, even if their consent was still needed for constitutional change, the withdrawal of support by the British government would, as one academic paper explains, "in itself lead to an erosion of the Unionist majority, since the obvious next step... would be to seek terms as an Irish national minority" and for those who didn't like the outcome to "leave for Great Britain". Having come up against a brick wall in London, Sinn Fein now appears to have concluded the EU might take on that role instead.

Sinn Fein ought to have realised by now that, as a UK representative told his government in the early 1970s, the only prospect of Irish unity lies in "the seduction, not the rape of the North". It's a disagreeable image, but the point stands. His own prediction was that "the south will, I suspect, be a long time a-wooing, if they ever start". SF certainly hasn't. Its charm offensives always end up by having more offensiveness than charm.

Think of it as a relationship between any couple. They split up years ago, one partner wants to get back together, and the other knows it, but isn't ready, and may never be ready, or has absolutely no interest in reconciling and repeatedly makes it clear. Still the other partner keeps going on at them, sometimes threatening, sometimes begging, to just lie back, relax, and let the inevitable happen. At some point it becomes harassment, and that point is now.

It's got to a stage where Unionists would be perfectly justified in taking out a restraining order.