London is still said to be open to an Irish Sea border for regulations

Britain has long said it was committed to las t December’s border backstop, but also that it did not accept the EU’s legal interpretation of it.

The issue gets confusing because London has repeatedly emphasised that it will reject a border in the Irish Sea, but in fact it seems committed only to avoiding a customs border.

It is still being reported by journalists who are close to the thinking of UK teams that Britain is trying to accept a regulatory border in the Irish Sea.

The inescapable ultimate logic of this is that Northern Ireland can never leave the single market and customs union. Of course Dublin and the EU do not put it like that and say it is only a backstop that applies if there is no acceptable deal. But this is misleading because they will not accept Northern Ireland being part of an arrangement that is less close to the EU trade set-up and involves divergence. It is a reflection of the precarious position of the government that a Tory administration is trying to find a way to facilitate this, albeit obliquely.

Trade experts say that regulatory divergence would in any event be minimal, but that is beside the point, for the same reason that Dublin does not accept minimal regulatory divergence at the point of the land border. It is the principle.

Agreeing to such a thing would mean that, unforgivably, London was more determined to give reassurance and legal commitments to another jurisdiction than to its own territory.

If that is so then it is hard to see how the Conservative and DUP deal can hold. The DUP is in a grim position because making threats to the Tories just guarantees enemies.

Sadly, no-deal or a new Conservative leader who will scrap the backstop look like the least bad outcome from a unionist perspective, for all their uncertainties and drawbacks.

Meanwhile, the interventions of David Trimble, Graham Gudgin and Ray Bassett via Policy Exchange are crucial and welcome, but even so the Omens do not look good.