Ben Lowry: Jeffrey Donaldson sends a robust message on the backstop in a speech to a think tank in Dublin

Sir Jeffrey Donaldson, who represents Lagan Valley at Westminster, spoke to the Institute of International and European Affairs in the Irish capital.

At the outset of his address, he said of his audience: “The members of this institute are amongst the most experienced civil servants, diplomats, business leaders and opinion formers in these islands.”

Sir Jeffrey’s initial tone was, in the spirit of such a gathering, diplomatic. He joked about party chief whips, of which he is one, and noted that Eamon de Valera had represented South Down, including the Mourne mountains from where his family hails, as an absentee member of the post partition Stormont.

Sir Jeffrey referred positively to the August 2016 joint letter from Arlene Foster and Martin McGuinness to the prime minister, which also seemed to be a reconciliatory gesture to the IIEA, because unionist critics say is set the scene for ‘special status’ and the backstop.

He even made explicit DUP acceptance of the status quo that has emerged from the 1998 Good Friday Agreement, that the party had so vehemently opposed (setting Sir Jeffrey on a path towards departure from the Ulster Unionists).

“As someone who wore a uniform to face down the terrorist threat from both loyalists and republicans, I stand by and continue to support the political institutions created under the Belfast and St Andrews Agreements,” he said. “I always will.”

Lest that seem to be a personal remark, independent of DUP colleagues, he added: “My party always will.”

Sir Jeffrey also seemed so careful to avoid sounding confrontational to his Irish audience that he even referred to DUP efforts to restart devolution without pointing out it was Sinn Fein who brought it down (and will not let it return without an Irish language act).

“We are also working hard to bring about the restoration of the devolved government at Stormont,” he said, “with it return of the North-South institutions and full working of the British Irish Council.”

But Sir Jeffrey’s emollient words seem to have been softening the blow of the more hard hitting core message of his address: utter DUP opposition to the backstop.

It might seem obvious that the party rejects the backstop, but its language seemed more ambivalent earlier this year. In March, Sir Jeffrey spoke on RTE about how the DUP was waiting to see whether the attorney-general Geoffrey Cox could give assurances on the backstop that would satisfy them. The DUP seemed open to supporting the Withdrawal Agreement.

On Thursday, any members of the Dublin audience hoping that the DUP was still open to reassurance were to be disappointed. Sir Jeffrey had warned them at the start of the address that he was, “as you would expect from and Ulsterman”, going to be straight, that he was there with a message, and one that came from his party leaders.

“[The backstop] has been rejected by the House of Commons on three occasions and every shade of unionism in Northern Ireland opposes it,” he said when the speech got to its central theme.

“If we are to lay a foundation which the next generation, both north and south can build upon, then we must recognise, before it is too late, that there is a seismic problem with the backstop.”

Sir Jeffrey, who had surprised some of us earlier this year by referring at Fine Gael’s conference earlier to “our friends” (if this Irish government, which so often seems to be at one with republicans, even on the issue of the murderous legacy of the Troubles, is acting like our friends, what would our enemies be like?) was now less polite about the administration.

“Leo Varadkar and Simon Coveney knew from an early stage that the border was sensitive but they viewed that not as a delicate matter where consensus was needed but rather as a bargaining chip which could be used by Brussels,” he said.

“At a time when cool heads were needed in Brussels, Leo Varadkar was photocopying articles from the Irish Times about a 1972 Provisional IRA bombing of a customs post.

“He was sharing this article amongst the other EU leaders. But to what end? What was his point? The border post was targeted by republican terrorists because it represented the UK government not because we were outside the EU.”

Sir Jeffrey’s was trying to reach movers and shakers in Dublin, but such long belated criticism of Ireland, in its capital, will be music to the ears of unionists who feel that the customs bomb picture episode by Varadkar was never challenged by the media or by London.

If the UK was inclined to use the tactics the Taoiseach did over customs attack, it might show President Donald Tump and his hawkish national security advisor John Bolton pictures of decades of Irish terrorism, and mugshots of IRA killers Dublin refused to extradite, leading to ongoing border murders, year after year.

It would be reminding that American duo of why there was a hard border – and unearthing whether Mr Trump really supports the backstop, as Mr Varadkar implausibly claimed.

“The same republican mindset attempted to murder a police officer last week in East Belfast by placing a bomb under his car,” said Sir Jeffrey, providing more music to ears long deprived of it, coming after the British government stayed predictably mute when Mr Coveney had the nerve to interfere in the dangerous situation in the Northwest (he said the detention of the dissident Tony Taylor, who abused his release on licence by returning to illegal paramilitary activity, was contributing negatively to relations in Londonderry).

Sir Jeffrey said: “At the outset I touched on the need to win both hearts and minds of all sides if any agreement is to be successful.

“Yet, the Irish government sought a solution to Brexit which they must know does not have the support of unionists – the so called backstop. They abandoned the politics of consensus and instead now find themselves claiming to be a guarantor of the Belfast Agreement, whilst being at loggerheads with Westminster and unionism.”

Sir Jeffrey’s speech comes after a period of dominant political support for the backstop (still reflected in the BBC decision to have a panel of three business people on Thursday’s The View, not one of whom expressed the fears hundreds of thousands of us have about it).

The DUP has laid down its marker, at a time when Boris Johnson is more likely than ever to be prime minister, after Thursday’s vote.

Does Mr Johnson’s contempt for the backstop, articulated at the DUP conference, still stand, or will he accept it, as he did in March, and push a variant of it through?

• Ben Lowry (@BenLowry2) is News Letter deputy editor