Besides being prime minister, Boris Johnson is the self-appointed minister for the Union. It is an honorific title rather than a real ministry and campaigners against Whitehall waste should take heart that it comes with no additional salary. Next year this unionist in Number 10 risks the possibility of having to deal not only with Nicola Sturgeon in Scotland but Sinn Fein’s Michelle O’ Neil as first minister of Northern Ireland.

Johnson’s Northern Ireland protocol has dealt a blow to the DUP’s credibility. The governing principle behind the agreement – that a heavily regulated sea border should be erected to divide Northern Ireland from the rest of its own country in order to honour the sanctity of an open border with the Republic of Ireland – was offensive in principle to the province’s unionist majority. Yet more salient, it is proving practically calamitous to all Northern Irish citizens without discrimination to their political and identity preferences.

Recent opinion polling suggests the DUP’s popularity has sunk to the extent that it is now only one percentage point away from becoming the province’s third most popular party (Sinn Fein has opened a 5 percent lead). Perhaps it is a crumb of comfort that their Ulster Unionist Party rivals aren’t the beneficiaries, but Jim Alister’s Traditional Unionist Voice is picking up the share of the unionist vote that is splitting rather than shrinking. The fall of the main Unionist party is something the minister for the Union needs to consider.

Ever since signing the protocol, Boris Johnson has squared the circle (in his own mind) of how it preserves the kingdom’s unity by appearing to suggest it does not do what it patently does do. Back in November 2019, he sought to reassure Northern Irish businessmen that they could put customs declaration forms “in the bin” because there will be “no barriers of any kind” in the Irish Sea. He is a man of many gifts, but has no future as a business consultant.

Nor has the reality of that sea border improved Johnson’s grasp of the detail. At Wednesday’s PMQs, he endeavoured to reassure Ian Paisley, that he would do whatever it takes “to ensure there is no barrier down the Irish Sea” so that businesses “can continue to do business unfettered between Northern Ireland and the rest of this country.” Sometimes the prime minister misses the benefit of his former Daily Telegraph sub-editor, and in this instance “continue to” ought certainly to have been marked for deletion.

Last month the chief executives of the UK’s six largest supermarket chains, including Tesco, Asda, Sainsburys and Marks & Spencer, which collectively supply the majority of retail food sales Northern Ireland, wrote to Michael Gove (in whose capacity as Cabinet Office minister the protocol was negotiated and is handled) explaining that the protocol’s regulations were resulting “significant disruption to food supplies” and that he needed to tell the EU that what had been negotiated was “unworkable.”

A stay of execution is not to be confused with a conviction overturned

The current supply problems are as nothing compared to what the province can expect after 31 March when the “grace period” reducing the bureaucracy for food and animal-origin products is scheduled to end. Nor are the problems confined to supermarket shelves and food on the plate. For many British mainland-based companies, having to handle the bureaucracy of a separate Northern Irish system is an effort greater than the gain of selling to a relatively small market of 1.8 million people. Online shoppers are discovering that Amazon keeps adding to its list of things that it will no longer ship to Northern Ireland. Small companies with limited resources for bureaucratic process are giving up.

The glib response is to suggest the EU’s Single Market is a big place, and the good people of Belfast and Ballymena will soon find the products they want supplied to them through the border that isn’t a border rather than across the commercial border that separates them from their own country.

Amazon keeps adding to its list of things that it will no longer ship to Northern Ireland

There are principled objections to being sold a future in which everything is imported from abroad and nothing traded from within one’s own country. Regardless, it is not true that everything grown, made, or added-to in Great Britain is also available in the EU, to the same quality, to the same specifications and design, the identical taste, and at the same (or lower) price. It is fatuous to imagine that among its many achievements the EU has cloned the British economy and that those producing stuff in Great Britain can all call it a day and retrain as customs officials.

Johnson and Gove have a choice of politically unpalatable options. They can seek to save the Northern Ireland economy (and the fortunes of the DUP) by breaching their own international treaty and revoking the protocol. To say that this will come with diplomatic consequences is to parody under-statement. The EU’s retaliation will not be limited to Northern Ireland. Joe Biden will do more than tweet about it.

Yet, with amendment the principles of the Protocol could be preserved without the most punitive parts of it being applied. In particular, the provisions determining goods that are “at risk” of entering the EU Single Market in the Republic of Ireland having crossed from Great Britain into Northern Ireland needs to be more restrictively defined. At the moment, almost everything crossing the Irish Sea into Northern Ireland falls within the “at risk” scope, however inconsistent pro-Commission spin can be this issue. To give an example: the vast majority of medicines coming over from Great Britain into Northern Ireland are going into the NHS, which exists neither in the Republic of Ireland nor anywhere else in the EU. Consequently, they are going into a pharmaceutical supply chain that stays in Northern Ireland. There is no “at risk” possibility. “At risk” has been defined and taken to extreme levels. Unless it is confined, the protocol will never be workable.

The second option – which the prime minister claims he has not ruled-out – is to invoke the protocol’s Article 16. Having (fleetingly) announced it was doing so itself last week to prevent Covid vaccines crossing the border, Brussels has squandered the moral high ground on this issue. But that does not mean it will reply “good idea” when the UK announces it. How and when would London propose exiting Article 16?

The third option, set out in Michael Gove’s letter to the European Commission’s vice-president, Maroš Šefčovič , is to kick the can down the alley by seeking an extension to the grace period for supermarkets and their supplies, chilled meats and Royal Mail parcels from beyond the end of March until “at least” 1 January 2023. Commission sources are briefing that they do not care for the “tone” of Gove’s suggestions. But politically, what he is proposing is deliverable given that throughout the withdrawal saga Brussels has demonstrated flexibility on timing, but not on systems, procedures and processes.

The problem is that what is politically easiest is not necessarily far-sighted. Companies plan their supply chains months and preferably years in advance. Being promised chaos in a couple of years rather than a couple of months is an invitation for them to cut Northern Ireland out of their long-term plans now. A stay of execution is not to be confused with a conviction overturned.

In terms of raw political calculation, what Number 10 wants above all else is not to have to concede another Scottish referendum to a Nicola Sturgeon emboldened by the likely result of the next Holyrood election. Strategists inside Downing Street believe that staving off the SNP’s mono-demand will be made much harder if there’s a Sinn Fein First Minister at Stormont. Elections are due there by May 2022.

Success for Sinn Fein will result in demands to trigger a referendum in Northern Ireland under the terms set out in the Belfast Agreement. Boris Johnson may not fear for his job over Ulster, but if Arlene Foster loses hers, and that leads to him losing Scotland, the boy who wanted to be “world king” may end his reign as lord of a sadly diminished isle.