Andrew Lilico is an economist and political writer.

The UK and EU appear still to be bogged down on the question of the Northern Ireland border backstop. The EU and UK have agreed (rightly or wrongly) to produce an agreed text for a “Withdrawal Agreement” covering citizens’ rights, the financial settlement – and the border. The EU has proposed a legal text that (in the absence of other agreed solutions) would keep Northern Ireland inside the EU’s Customs Union and Single Market whilst the rest of the UK left them, with customs checks taking place at the Irish Sea. Let’s call this the “Irish Sea border” proposal.

The UK regards the Irish Sea border proposal as unconscionable, a de facto annexing of Northern Ireland by the EU, the kind of proposal that no Prime Minister or British Government could ever accept. Indeed, the Commons recently passed an amendment to the Trade Bill which barred any agreement to put Northern Ireland into a separate customs area from the rest of the UK, and did so with such unanimity that a division was not even required.

EU diplomats and officials suggest that, unless the UK accepts the Irish Sea border proposal, there can be no agreement on withdrawal terms, or indeed any future partnership. This seems patently absurd to most British onlookers.

The UK has guaranteed that, even in the event of no deal, it will not impose border checks at the Northern Ireland land border. Ireland’s Taoiseach, Leo Varadkar, revealed last week that the EU has promised him, repeatedly, that it will not impose any border checks at this border even in the event of no deal.

So all parties agree that there will be a soft border. They merely don’t agree on how. But since each has guaranteed to maintain a soft border unilaterally, even without the cooperation of the other, surely that ought to suffice as a “backstop”? Threatening that there will be no deal and a total breakdown of relations because the UK and EU can’t agree on a joint way of doing what we both guarantee, in any event, we’d do individually just seems absurd.

The EU says the UK should “de-dramatise” the idea of an Irish Sea border. Since goods would be on planes or boats anyway, they claim it shouldn’t be seen as that big a deal – no violation of sovereignty, breaking up of the UK, or improper barrier to commerce.

Checks for those leaving the island of Ireland on planes or boats – persons, not goods – do of course already occur, but at what we might call the “Celtic Sea border” (between Ireland and France) rather than the Irish Sea border. Ireland is not in the Schengen Area, instead being in a Common Travel Area with the UK. So people can be subject to passport checks at the “Celtic Sea border”.

So if there must be checks done on goods leaving the island of Ireland, is it not more natural that they take place crossing the border where checks on persons already occur — the Celtic Sea border?

Lo! Did I hear someone say that for a Briton to suggest this is some kind of threat to the integrity of the EU’s Single Market, violates the sovereignty of Ireland, and perhaps is even insulting? But why? I thought we were supposed to believe that checks of goods leaving the island of Ireland should be “de-dramatised” and were no threat to sovereignty or the integrity of markets, let alone insulting?

Indeed, a Celtic Sea border should be less problematic, in sovereignty or market integrity terms, than an Irish Sea border. After all, an Irish Sea border would place checks within a country, whereas a Celtic Sea border would be checks between one country (Ireland) and other countries (the rest of the EU), where such checks (on persons not goods – but checks on persons would be the Single Market in services equivalent) already occur (in relation to Schengen). One could hardly claim that these would break up the Single Market but that an Irish Sea border would not break up the UK market.

Others might say: “But this isn’t Ireland’s problem.” Howevrm the current impasse results in no deal, that will absolutely be a problem for Ireland – perhaps more so than anyone else. If a Celtic Sea border would get us to a solution, mightn’t it be worth considering?

How could this idea work in practice? Well, the Irish and UK governments could agree that they would not impose any stop-and-check controls at the Northern Ireland land border, but would instead seek to enforce regulatory and tax differences across the border in much the same way that regulatory and tax compliance is delivered internally within countries — through audit and whistle-blowing and on-site checks and intelligence operatives. That could be facilitated by allowing the Northern Ireland assembly, if it chose, to coordinate Northern Ireland’s regulations with those prevailing in the Republic in a few key areas, such as animal and plant health and welfare (which constitute a high proportion of border checks internationally).

If the EU’s view is that such methods could not be relied upon, the scope for non-compliance could be limited by having Celtic Sea border checks on goods. That would also have the advantage of meaning the audit, whistle-blowing, on-site checks and intelligence techniques mentioned above would only need to focus on Britain and Ireland, rather than being expanded to cover the whole EU.

We ought not to require any more Ireland – Northern Ireland border “backstop” than the undertaking that all sides have already made that, even in the event of no deal, there will be a soft border. But if some further “backstop” is required, a more natural and less problematic one would be a “Celtic Sea border”, where checks on persons already occur (apparently without threatening the integrity of the Single Market in Services), combined with cooperative away-from-the-border enforcement mechanisms on the island of Ireland.

On the other hand, if people really think a Celtic Sea border is an inconceivable break-up of the Single Market, a threat to the sovereignty of Ireland and an insult to the people of Ireland, perhaps that might help Ireland’s Government, just a little, to understand how we in Britain think about the Irish Sea border idea?