A former senior Stormont official has issued a highly critical broadside against the UK government over its attitude to the Northern Ireland Protocol.
Andrew McCormick was a lead figure for five years in the Brexit negotiations and their impact on Northern Ireland.
Now he has said the UK government knew full well what the Protocol entailed and that it is chiefly responsible for what was agreed with the European Union in October 2019.
He also dismissed any notion that the Protocol was anti-democratic.
"Responsibility for the Withdrawal Agreement of 2019 and the Protocol lies fairly and squarely with the UK government," Dr McCormick has written in an article for the Constitution Society.
"It is hard to imagine anything (other than Brexit itself) with greater democratic legitimacy under the UK constitution than something that was the very centre of the manifesto on which a government secured a clear majority in a general election.
"There is little credibility in any argument that the UK government either did not anticipate the implications of what it had agreed, or was constrained and unable to choose any other option.
"The facts and choices had been spelt out clearly over the whole period from 2016 onwards and the detail of the provisions (notably most of the applicable EU law contained in Annex 2 to the Protocol) were known at latest in autumn 2018.
"And the time constraint to 'get Brexit done' was entirely self-imposed. Indeed, as some have pointed out, the UK government could not explain the Protocol without having to explain properly the wider consequences of Brexit."
Dr McCormick retired last year as Director General of International Relations for the Northern Ireland Executive Office.
Between 2017 and 2020, when the North's institutions were suspended, he regularly attended UK ministerial meetings, and until May 2021 represented the Executive during meetings of the EU-UK Specialised Committee on the Protocol.
Dr McCormick was involved in the Mayhew talks of 1992-93 and worked on the implementation of the north-south institutions established by the Good Friday Agreement.
He was involved in multiple meetings with the European Commission Task Force on Brexit during the Withdrawal Agreement talks.
Dr McCormick said there was "no basis" for the argument that cross-community voting should be required for the application of the consent provisions in the Protocol.
This was because international relations were not a devolved issue, as was made clear by a number of UK acts.
He said it was clear that the UK government and the EU had jointly "considered the implications of the absence of cross-community consent, and made a clear agreement that the Protocol would continue to apply even if only a simple majority in the Assembly approved".
He said there was evidence that the Protocol "does have the consent of a simple majority both of the electorate in Northern Ireland and the Assembly".
Dr McCormick pointed out that in the general election of December 2019, there were 444,227 votes for the parties which voted for the implementation of the Protocol - and against the use of Article 16 - in the Assembly debate of 30 December 2020.
There were 337,874 votes for the parties that opposed the Protocol (a 56%/42% split).
"So, it is reasonable to infer that, had consent been sought in October 2019, there is a very strong likelihood that the Assembly would have approved the Protocol."
Dr McCormick warned that nationalists were still required to acknowledge unionist concerns.
"Irish nationalists and republicans need to recognise that stability and security for all communities depend on confidence.
"Even if it can be argued that unionists should have seen more value in the 1998 Agreement, realpolitik should acknowledge that the unionist community has limited (and for some at least, diminishing) confidence in the settlement, and that the Protocol represents a very real challenge to their confidence.
"It cannot be denied that Brexit and the Protocol created and create very challenging sets of issues, and neither was explained properly."
Dr McCormick said the government of Boris Johnson should have made it clear in October 2019 what the implications of the Protocol were, and that the Irish Sea border would be made harder the more the UK diverged from EU standards.
"It is hard to see any basis for tolerating the unwillingness of the UK government ministers to invest fully in a fact-based, problem-solving approach to a highly complex and sensitive task.
"This exacerbated the issues of confidence that arise from Brexit when the clear responsibility of London and Dublin was (and is) to build confidence. But that requires honesty."
Earlier today, the UK's former chief Brexit negotiator David Frost said the Northern Ireland Protocol has left the Good Friday Agreement "on life support" and needs to be renegotiated or scrapped.
Speaking a week before the Northern Ireland Assembly elections, he said the protocol had been the only way to deliver Brexit by the time Boris Johnson became British Prime Minister in 2019.
Accusing the EU of treating his negotiating team as "the supplicant representatives of a renegade province", Mr Frost said his government had faced the choice of accepting the Protocol or walking away and failing to deliver Brexit.
He added: "At that point we would have seen, at best, a second referendum, quite possibly Brexit taken off the agenda for good, and who knows what consequences in our domestic politics."
Additional reporting: PA news