The momentum towards the UK triggering Article 16 of the Northern Ireland Protocol is building.

Once COP26 is out of the way, there are strong expectations that London will make its move.

Despite the ongoing technical talks between European Commission and UK officials in London and Brussels on the EC's package of measures to ease the implementation of the Protocol, the UK Brexit minister David Frost continues the rhetorical assault on the Protocol and its provenance.

This week the Financial Times reported that Downing Street was expanding its legal advice on triggering Article 16.

"A lot of the expectation is due to the statements of Frost and the very dismissive approach he takes to the efforts of the EU to try and find practical solutions to the implementation of the Protocol," says one EU diplomat.

"The UK keeps waving the threat of Article 16, and the more they talk about it the more people are now beginning to believe them. So there's an air of inevitability about it."

Britain's Brexit negotiator David Frost

That, of course, may be the strategy in order to extract more concessions. Or, Boris Johnson may not yet, in true fashion, have decided which course of action to take: strike a deal which is the best deal going, or trigger Article 16 and keep instability and crisis to the fore.

The Protocol has also become entangled in the fisheries row with France. David Frost met the French Europe Minister Clement Beaune in Paris on Thursday to resolve a bitter row over licences for French vessels to fish in UK waters.

The meeting itself appears to have been inconclusive, with contradictory briefings from both sides afterwards. "The French said they're looking forward to new proposals from the UK based on a revised methodology," said one diplomat briefed on the meeting, "and the UK saying there is no revised methodology".

Frost raised the Northern Ireland Protocol, repeating the complaint that the UK’s concerns were not being met in the technical talks with the Commission and that London would have to consider its options.

Beaune, in turn, said this was a matter for the UK and Brussels, but that France supported the Commission’s position, according to a source briefed on the Paris meeting.

The UK continues to demand that the European Court of Justice, in arbitrating any disputes, be removed from the protocol.

The technical talks on the Protocol do not appear to be bearing much immediate fruit either.

The European Commission agreed to the talks only on the basis of the package of measures on medicines, customs, agrifood checks and an oversight role for Northern Ireland institutions and stakeholders published on October 13 by Maros Sefcovic, the EU’s chief negotiator.

While there has been some progress on reducing customs formalities, the Commission is putting significant effort into ensuring that whatever agreements emerge remain bespoke solutions for Northern Ireland, and that the UK won’t see similar easements for GB trade into the EU in general.

According to a number of sources, the UK has tried to expand the agenda of the talks to bring in other Protocol issues, such as VAT and state aid.

And the UK continues to demand that the European Court of Justice, in arbitrating any disputes, be removed from the protocol.

According to one EU source, British officials have repeatedly attempted to get the ECJ onto the agenda, and to push it up to the higher political level, so that it is discussed by Frost and Sefcovic.

"They're definitely honing in on that question," says the source.

The Commission has resisted, and this seems certain to continue, despite some fevered speculation that both sides might agree an extra layer of arbitration between Northern Ireland and the ECJ.

"The ECJ is fundamental and not negotiable," says an EU diplomat. "So all this talk of fudges and intermediary bodies and arbitration before things get to the ECJ - this was never discussed by the Commission and the member states."

Furthermore, the EU is insisting that whatever easements are agreed in implementing the protocol will be conditional.

This is because trust has sunk to such levels that member states will demand guarantees that the UK will complete infrastructure at Northern ports, including Border Control Posts, even if the need for checks and controls is reduced significantly.

"There is the difficulty in making sure that whatever the UK signs up to, they don't end up paying lip service to it," says the source. "The Commission has presented member states with preconditions, including building the border posts. If they ever need to start implementing some checks because there's an abuse of the system, those checks can be resumed."

The Irish government now feels that insisting on the Irish border being sorted in the divorce negotiations has been vindicated by Britain's failure to comply with the treaty.

In the background, David Frost continues to lambast what he clearly regards as the Original Sin: the notion that the way to solve the Irish border issue was for Northern Ireland to remain aligned to the EU single market and customs rulebook.

This is not just one person’s opinion. The UK government’s official position, as delineated in the Command Paper of July 21, expressly attacks the basis for the protocol.

"The [UK] Government does not accept – and has never accepted – that the Northern Ireland Protocol was the only means of protecting the Belfast (Good Friday) Agreement, including this North-South dimension," the Command Paper states.

"It is clear, and was clear at the time, that other solutions are foreseeable both within and outside the framework of the Protocol that subsequently emerged."

These refer to the "alternative arrangements" which were long a feature of the Brexiteer toolbox and which Boris Johnson unsuccessfully pushed in the weeks leading up to the protocol being agreed in October 2019.

The Command Paper argument is that, had the UK not been in such a weak negotiating position at that time, due to the Benn Act which prohibited exiting the EU with No Deal, then these hi-tech solutions to avoid infrastructure on the land border would have worked.

The paper goes a step further. The genesis of the Northern Ireland Protocol, and the idea of the region remaining aligned, is the EU-UK Joint Report of December 2017, in which the UK formally accepted alignment as a potential solution (in other words a "backstop") if alternative arrangements, or if the nature of the future free trade agreement, did not in themselves dissolve a hard border.

The Command Paper said that the power to determine if the latter two solutions worked or not lay with the EU. This was not just a problem for Northern Ireland’s place in the United Kingdom, but it would also "force the whole of the UK into the EU customs union and the Single Market for goods."

That these scenarios would end up in the divorce treaty, the paper says, and not be solved by the future trade relationship, further locked the UK into a trajectory that would end up with the protocol, which was part of the divorce.

The fault on that score lay with Theresa May, the paper concludes: "In the then Prime Minister’s letter to President Tusk of 19 March 2018, the Government conceded that there would indeed be operational legal text for at least the 'backstop’ option."

Theresa May's government conceded the need for legal text on a backstop option

This then meant that when Boris Johnson took over in July 2019, he found himself "in a situation in which there had been assumptions built in for more than a year that any agreed arrangements had to fit into the contours of the proposed ‘backstop’."

These ideas were further amplified in a detailed paper on Monday from Policy Exchange, a pro-Brexit think tank, written by Roderick Crawford, but with a foreword by David Frost.

The European Commission is understood to have been told another Frost intervention was on the cards and this prompted Maros Sefcovic to take to the pages of the Daily Telegraph the same day to warn Britain against refusing to engage on the EU’s flexibilities and instead "embark on a path of confrontation."

Frost's contribution to the Policy Exchange Paper, entitled The Origins of the Current Crisis, includes the revelation that he had considered resigning when the Joint Report emerged (at the time he was an advisor to the then Foreign Secretary Boris Johnson).

He said the UK "drifted" towards the EU position on alignment not just because of its "extremely weak" negotiating position following Theresa May’s disastrous spring election in 2017, but also because British civil servants had been dulled by 45 years of membership and, in effect, did not know how to strike a tough negotiating stance.

With time passing, Irish and EU officials believed London was lingering in a comfort zone.

As a result, the Original Sin had condemned Britain to a disadvantageous position before, during and since the conclusion of the Protocol on Northern Ireland. "The Joint Report," Frost wrote in the foreword, "is arguably the text that has done most to shape the terms of this country’s exit from the European Union."

The intellectual argument is developed further by Roderick Crawford. The Joint Report was the result of the EU swallowing the Irish government’s analysis of the threat posed by Brexit as primarily being about the risk to all-island cooperation and economic activity, with no account taken of east-west commerce or the unionist position.

Crawford argues that this was exacerbated by the so-called "mapping" exercise of 2017, when EU, Irish, British and Northern Irish civil servants forensically went through 140 areas of north-south cooperation to see which elements had been underpinned, or enhanced, by the same EU legal framework on both sides of the border.

The EU’s position on Ireland, therefore, "was built not only on an incorrect reading of the Belfast Agreement but also on assumptions and exaggerations that misrepresented the scale of North-South cooperation and its dependence on common EU legal and policy frameworks."

What made matters worse, says Crawford, was the UK capitulating to the EU’s sequencing of the negotiations, i.e. that the Irish border issue be resolved within the divorce treaty, and not the future relationship agreement, which was London’s preference.

That meant that the UK could no longer solve the problem bilaterally with Ireland. "This represents an early lost opportunity to grasp the nettle in the negotiations. It is largely the consequences of that failure that the UK is now engaged in correcting," writes Crawford.

It is highly questionable that a more robust UK negotiating strategy would have prevented the sequencing issue.

It is also unlikely that the EU would have agreed to a solution to the border sponsored by those pushing alternative arrangements (the EU certainly didn't accept a customs border on the island even as the prospect of No Deal beckoned in October 2019).

The Irish government now feels that insisting on the Irish border being sorted in the divorce negotiations has been vindicated by Britain’s failure to comply with the treaty, and that had the border been left to the trade negotiations then London would have used it as leverage to get a frictionless trade without the obligations of EU membership.

The Commission has been exploring its options if the threat is acted upon.

That is not to deny that the UK felt badly done by in the run up to the Joint Report. In the autumn of 2017 London was evolving its position on how to avoid a hard border, preferring that both sides agree outcomes as opposed to hard legal obligations in the Withdrawal Agreement.

While that deliberation was proceeding, the EU and Ireland grew increasingly impatient that London had not fully internalised that leaving the single market and customs union would place a border somewhere, and that precise solutions were needed.

With time passing, Irish and EU officials believed London was lingering in a comfort zone.

When a Commission working paper, circulated in early November 2017, contained the notion of Northern Ireland not diverging from single market rules, London was horrified, and essentially felt ambushed.

The bad blood that followed meant the negotiations that led up to the Joint Report were among the most bitter so far. Irish officials were part of the negotiation, and took a hard line on the need to have an operational solution to avoiding a hard border.

As the deadline to agree the Joint Report approached, Dublin conceded that "no regulatory divergence" could become the third option behind alternative arrangements and the future free trade deal (option C, as it was called, which later became known as the backstop).

What got the Joint Report over the line was a last minute, and highly Jesuitical, fix, in which "no regulatory divergence" from single market rules was replaced by "continued alignment" with those rules. The UK believed that "alignment" was more of a sovereign choice.

The DUP scuppered the first text when they learned what it might entail, and an adjusted document, with a new paragraph committing the UK to ensuring unfettered access for goods from NI to GB, was agreed by both sides on 8 December, 2017.

Crawford says this will be seen as a pyrrhic victory for Dublin. "The EU’s negotiations have been widely seen as a major success for both Brussels and Dublin. This report shows that to be far from the case. The EU ‘forced’ the UK to accept a solution that worked legally for the EU but worked neither operationally nor politically in the context of Northern Ireland."

Within 48 hours of the Joint Report being signed, the Brexit secretary David Davis had told the Andrew Marr show it was not legally binding.

One Irish official, closely involved at the time, dismissed any notion that Dublin was victorious. "Everything on our side was about damage limitation," said the official.

The Joint Report formed the basis of the first Northern Ireland Protocol. When it was converted into a legal text in February of 2018, Theresa May swiftly rejected it, saying famously that no British prime minister would accept a customs border down the Irish Sea.

Ironically, it has since emerged that the Joint Report was not automatically going to be part of that first Withdrawal Agreement draft which Theresa May rejected.

EU officials had pondered that it might come at a later stage, and prepared to have a one-page placeholder on Northern Ireland that would be added in due course.

"We hadn’t thought about having to put this in as part of the legal text of the Withdrawal Agreement in February [2018]," says one official closely involved at the time. "Because we weren’t there yet. You had this long coordinators' process [involving the UK’s Olly Robbins and Sabine Weyand, Michel Barnier’s deputy, who worked separately on the Northern Ireland issue].

"We were only putting the pieces together. We knew regulatory alignment was a core element, but we didn’t have a legal text in front of our eyes. We thought it would end up in building blocks, in commitments, in cross referencing."

Britain's former Brexit Secretary David Davis

What prompted the change of approach were, primarily, Irish concerns that the UK could not be trusted. Within 48 hours of the Joint Report being signed, the Brexit secretary David Davis had told the Andrew Marr show it was not legally binding.

In fact, an Irish official drew up a rough legal draft that reflected the Joint Report even before the Christmas break in 2017. Once member states returned in early 2018, they agreed that the Joint Report should be nailed down in the first draft of the Withdrawal Agreement.

This version of events is corroborated by a senior Stormont official, closely involved at the time. "The Davis interview was what provoked Europe," said the official. "They were probably going down that route anyway, but it provoked them all the more to turn the Joint Report into a legal text as quickly as possible. Because for them, it was deadly serious."

Dublin believes Frost is now rewriting history, and that what officials refer to as "buyer’s remorse" is no excuse for triggering Article 16.

This week, following close contacts between Dublin and Brussels, it was agreed that Ireland should sharpen its messaging on the Article 16 threat.

In the Dáil on Wednesday, the Taoiseach said triggering it would be "irresponsible and reckless" and would have "far-reaching implications" for relations between the UK and Europe, and the UK and Ireland.

The Commission has been exploring its options if the threat is acted upon. Those discussions have, until now, been internal. However, capitals are now being familiarised with what appears to be a menu of tougher measures, potentially including the termination of the Trade and Cooperation Agreement (TCA).

"There is some concern that the UK might miscalculate," says one diplomat, "that London might expect the response to be quite legalistic, maybe arbitration and an infringement procedure.

"And basically, not much would change. That there would be a month of consultations, and everything would sort of more or less continue. And that's not necessarily what would happen. There is some discussion of quite far reaching and quite radical responses."

Those responses remain in the realm of discussion and preparation. But most observers believe that the triggering of Article 16 would dramatically escalate the stand-off and deepen the instability in Northern Ireland, for businesses and communities alike.