Yet again, a prominent unionist - in this case Mike Nesbitt - is seeming to backtrack after merely discussing the idea of a united Ireland. Some unionist leaders have compromised, which, many forget, is what politics is for. Of course, subsequently their political stage began collapsing, but this state of affairs in unionism may not last for ever.

"Not an inch" is a unionist clarion call, but it might not serve the parties forever. Because of Brexit and of local issues, the political arena is changing rapidly, perhaps as rapidly as in 1972, when the old unionist majority Stormont parliament was suddenly demolished - by a Conservative UK Government, some have forgotten.

That memory should have been jogged when another Conservative prime minister proposed cutting Northern Ireland loose during Brexit negotiations by agreeing, albeit momentarily, to an economic border in the Irish Sea.

Some years ago, I wrote a history of the 1974 UWC strike, which ended with the collapse of the first power-sharing Stormont administration under unionist Brian Faulkner.

In that book, I defined unionism as seeking to maintain the British connection and, in parallel, to protect a Protestant way of life. I wondered whether these aims would ultimately remain compatible, because during the strike, there was enmity from Westminster towards unionism, loyalism in particular.

This manifested itself in the nationwide broadcast speech by Labour Prime Minister Harold Wilson, during the strike, in which he rounded upon the loyalists, calling them "spongers" on the British. (You can watch this on YouTube.)

There is evidence that the British public do not believe that Northern Ireland is as British as Yorkshire, which is why a border down the Irish Sea surfaced to the horror of the DUP.

They really should not have been surprised. That distancing undercurrent has been running beneath the British body politic for a long time, perhaps since partition.

The exasperation with Northern Ireland politics was a traceable thread running through many of the speeches commemorating the anniversary of the Belfast Agreement.

The suspicion must be that, given a face-saving opportunity, Britain might break free. Unionism should at least prepare for this eventuality, but seems systemically forbidden to brainstorm strategically. The Boers in South Africa thought that way until too late to salvage much.

However, at the beginning of the Troubles, no less a person than Ian Paisley saw what might be looming one day. In Opposition in the early 1970s, Harold Wilson - then Labour leader - appalled unionists by openly espousing Irish unity.

The governing Conservatives were not best pleased with the situation either. This was the context of what follows.

A fascinating meeting took place throughout much of the night of Thursday, November 25, 1971 in Belfast's Europa Hotel.

Ian Paisley was in the company of Desmond Boal, his close advisor, Henry Kelly of the Irish Times, Vincent Browne of the now-defunct Irish Press and Liam Hourican of RTE. It is documented, in the first definitive biography of Paisley, written in 1986 by authoritative journalists Ed Moloney and Andy Pollak.

Far into that night, Paisley eventually gave Liam Hourican of RTE an interview, in which he was asked that, if the Republic ditched the 1937 constitution (meaning the sovereignty claim over Northern Ireland) and changed certain other laws, whether he would he consider the prospect of being part of a united Ireland.

He replied, to the astonishment of the journalists, that such a situation would present an "entirely different set of circumstances".

In the Irish Press on November 29, 1971, Paisley was even more specific.

He said: "If the people in the south really want the Protestants of the north to join them in a united Ireland, then they should scrap entirely the 1937 constitution and ensure that the Roman Catholic hierarchy could no longer exercise an improper influence in politics. If this were done, then the Protestant people would take a different view ..."

He went on to say that this was not going to happen. But clearly he had, indeed, given the question consideration.

Reaction was interesting. Daithi O Conaill, then leader of the Provisional IRA, said that Paisley and republicans were allies in the cause of a new Ireland. Fianna Fail finance minister George Colley invited Paisley to help draft a new Irish constitution. The Irish Times postulated that, one day, Paisley might sit in the Dail.

Brian Faulkner, Northern Ireland premier, branded him the new darling of the republican Press and the UDA dissociated itself. The DUP leader retreated immediately. He had moved too far ahead and the episode was quietly airbrushed out of DUP history.

This was a distant hinterland to Paisley becoming First Minister in close association with Martin McGuinness. Paisley could not have foreseen Brexit, but he may very well have been aware that, somehow, the connection with Britain was not as secure as many believed. He was thinking strategically, but he, too, landed in trouble for doing so.

There remain many in the Westminster Establishment who, fairly or not, partly blame the intransigence of unionists for provoking a 30-year conflict, which tarnished the name of the UK in Europe, in the United States and beyond.

Unfortunately, it remains a heresy to articulate within unionism that the protection that the unionists seek and the peace they desperately need could be negotiated under the Irish tricolour and not the Union flag. It has been forgotten that orange was deliberately incorporated as one of the colours of the Irish tricolour.

If unionists want a "Protestant parliament for a Protestant people", they could profitably ask for it from those in Dublin, who, in the past, fashioned for themselves a "Catholic parliament for a Catholic people".

London will never again grant majority rule, but Dublin could. The era of religious politics has ended in Dublin. The constitutional claim is gone. Paisley's "entirely different set of circumstances" have now come about.

Perhaps some unionists are becoming aware of that.

Don Anderson is the author of 14 May Days: The Inside Story of the Loyalist Strike of 1974 (Dublin: Gill and Macmillan, 1994)

Belfast Telegraph