‘How do you eat an elephant?’ as the old saying goes. ‘One bite at a time.’ To the literalists, of which Northern Irish politics generates an over-abundance, I should make clear that I don’t advocate the slaughter of these magnificent beasts; I merely make the comparison that political objectives are realised by ingesting each morsel, piece by piece.

For someone who contends that Irish unity is inevitable, the weight of evidence to support my contention is now pleasingly apparent. No longer the preserve of idealists, or old men in the back rooms of pubs lilting The Dying Rebel, there is now constant ‘chatter’ about the prospect, notwithstanding the fact there is much work and discussion ahead.

But the remaining issues are, to woefully extend my elephant metaphor, eminently consumable. In part, because three things have started to happen. The first is that reunification is now mainstream in a way it simply has never been before in either Irish or British politics. The media, particularly on my easternmost side of the Irish Sea, has been awash with commentary about the issue for some time.

Check out Andrea Catherwood on BBC Radio Four’s ‘Analysis’ slot. Or Giles Fraser at Unherd. Or Dawn Foster in The Guardian. Or David McWilliams in the Financial Times. Or even, for that matter, the august pages of the New York Times.

This type of opinion-forming is important in seasoning the issue, thus familiarising and normalising the concept. Readers may disagree with my sanguine assessment about its inevitability, but you would need to be disingenuous in the extreme not to concede the issue of Irish unity has not now escaped from its traditional silo and out into the centre of the political debate.

This is timely as Northern Ireland’s future becomes part of a wider narrative around the constitutional disintegration of the UK, as Scottish secessionists galvanise themselves for a second tilt at independence. Campaigners were five percentage points from winning last time and it’s hard to underscore just how lackadaisical British politics is about what happened in the autumn of 2014.

It bears restating that all this was before Brexit. Now, with a reasoned desire to repeat the exercise, given 63 per cent of Scots wanted to remain in the European Union, they have an even stronger case. If this Parliament has been dominated by Brexit, the next will be overwhelmed by the UK’s constitutional future – or lack thereof. (Irish unity might seem small beer in comparison to ‘losing’ Scotland).

The second thing that has changed is that the issue of Irish unity now transcends Irish republicanism. It is becoming ‘deshinnerised,’ as I once put it. Other voices are coming to the fore. January’s ‘Beyond Brexit’ event at the Waterfront Hall was a case in point. I remarked at the time that it was the most important political gathering in Ireland for a generation, with reports that 2,000 attended, representing the broadest swathe of Irish nationalist opinion.

Most people there had been energised by Brexit, but also by the limitations of the devolved institutions and the antagonistic attitude of the DUP’s paleo-Unionism. Without rancour or chauvinism, these are voices from outside the usual political milieu talking about how their rights and prospects are better served in a new, all-Ireland setting.

Perhaps the most telling voice to discuss Irish unity in recent times is also the most surprising. ‘As soon as that decision is taken [a vote for Irish unity] every democrat will have to accept that decision.’ So said Peter Robinson at the McGill Summer School last July. It powerfully symbolised the normalisation of the debate. ‘I don’t expect my own house to burn down,’ the former DUP First Minister added, ‘but I still insure it because it could happen.’ (It was quintessentially Robinson; a lurid metaphor delivered bone-dry).

Accepting that Irish unity is plausible, regardless of whether he or Unionists ever want to see it happen, is a merely the logical conclusion of the evidence before all our eyes. Robinson is still a unionist and will campaign to remain part of the UK, but he pragmatically recognises those efforts may prove unsuccessful in the next few years. As ever in politics, its useful to have a Plan B.

And although he was, predictably, strafed by friendly fire for providing ‘music to the ears’ of republicans’ by speaking out, others in the DUP surely sense the way things are heading. The attendance of the DUP’s Simon Hamilton and UUP Leader, Robin Swann on a discussion panel talking about the prospect of Irish unity during last summer’s Feilie an Phobail was another small, but resonant step forward.

Clearly there isn’t much point being a Unionist if you do not pour cold water on the prospect of that arrangement ever changing; but the Kremlinology was instructive. The fact they were there at all was the main thing.

This is the smart move for Unionist politicians though, engaging with reality as they consider the difficult balancing act they will need to perform over coming years, making the case for the status quo but influencing the debate about Irish unity at the same time. Holding what they have, but future-proofing their political influence over the ground beneath their feet, whichever flag flies over it.

The issue of how those within Unionism who greet the prospect of Irish unity with something well short of alacrity can be won round to at least engage constructively with the prospect is a matter for everyone to assist with, the two governments and all the parties.

Unionists will instinctively hold to their doctrinal view, but if, because of Brexit, this now comes at the cost of livelihoods, then many will perhaps wonder if losing EU agricultural payments – and the family farm with it – is a price worth paying. Politics is forever a compromise, balancing what you hold dear with what you are willing to accept. Between what you want and what you can live with. Many people from Unionist backgrounds are already in this space and many more will, post-Brexit, join them.

Last but by no means least, we have the view of the British public. A recent Ipsos MORI poll showing British reaction to Northern Ireland made stark reading – barely a third of Brits were bothered about Northern Ireland remaining in the UK while a fifth positively wanted to see Irish unity. (In terms of raw numbers, this means there are twelve times more Irish nationalists in Britain than there are in Northern Ireland).

The third big change is that Irish unity has become an evidence-based argument. A solution to the problem that Northern Ireland will face surviving as an appendage to a post-Brexit British economy. Again, you need to be obtuse not to see this. Certainly the 4,000 workers at Bombardier – hitherto Northern Ireland’s largest private sector employer – are now painfully aware, with the planned closure of their Belfast site. If we could forget centuries of pained history and park the identity politics, the damage that Brexit will cause to Northern Ireland’s economy automatically makes becoming part a single Irish state, inside the EU, the economically rational thing to support.

So, here we are. Irish reunification is now firmly anchored in our political discourse, openly discussed by new and sometimes unexpected voices, who are making logical and pressing arguments. This is no longer the preserve of true believers or an issue about patriotic nostalgia. Irish unity is a progressive, rational and timely cause. Moreover, there is not a single decent argument against it. No-one is intelligently making the case for the status quo because there is no intelligent case to be made for it.

Northern Ireland was simply not built to last. That is the hard truth of it. It continues to serve – as it always has – as an interregnum, a staging post. The Good Friday Agreement proviso guaranteeing a border poll makes that plain enough. The first phase of the journey – the normalisation of the issue – is now complete. This brings us neatly to the next phase which is, as they say in engineering circles, ‘proof of concept.’

How exactly will a single Irish state come about? What new structures are required? How will it be financed? What’s a realistic timeline? How can those currently opposed to it be won round? And what constitutes a fair offer to them? These are the practical questions that supporters of unity must now address. (As, indeed, is a mature conversation about future Irish-British relations).

This is the guts of where the conversation now needs to turn, with southern Irish and British political elites stepping up. It is here where we have thus far faced a bottleneck, with too little critical thinking taking place. A promised White Paper from Fianna Fáil on unity has never materialised, with Fine Gael just as enthusiastic about treading water.

The British Government is in no hurry to make plans either, with Northern Ireland generally kept as far down Whitehall’s ‘to do’ list as possible. (Although Theresa May’s admission to Jacob Rees-Mogg that ‘we cannot be confident’ about winning a border poll perhaps tells us that the penny might be finally dropping about where all this lands).

The British Government may be keen to retain whatever creative ambiguity it can about the precise trigger for a vote, however, it seems inconceivable that Sinn Féin topping the poll in the next assembly elections and a majority for parties either committed to Irish unity, or, at the very least, committed to holding a plebiscite, could be ignored without displaying epic bad faith. (Indeed, if the SDLP captures the third European Parliament seat next week, it would be the first time a plurality of seats in a NI-wide election were won by advocates of Irish unity).

Ignoring what I, and many others, now see as an inevitable journey towards Irish unity merely serves to pile up political problems in the medium-term, while the only responsible course from both the two governments and all the parties – north and south – is to show willingness when it comes to moving the discussion on to practicalities and scenario-planning.

Irish unity is no longer a question of ‘if’ or ‘should’. We’re past that. It’s now about ‘how’ and ‘when.’