As the Brexit ratchet tightens, there is still no solution to the vexed issue of the Emerald Isle

The failure of the Brexit war cabinet to back Theresa May’s preferred option of a new customs partnership was portrayed as a victory for Leave and defeat for her.

In truth, it was neither. What happened on Wednesday was simply the latest turn of the screw, bringing the Government one painful step closer to the reality that now confronts it.

Recall that the new customs partnership, in which the UK collects tariffs on the EU’S behalf for goods destined for EU territory, has already been rejected by the EU. Even if Mrs May had persuaded her colleagues, there is little reason to believe the EU would have accepted an idea described as “cretinous” and “magical thinking”. But the desperation with which Mrs May and officials clung to such an improbable plan speaks volumes about the intractability of the Irish border conundrum and the grim alternatives.

The customs partnership was the cake-and-eat-it policy. Theoretically it left the UK free to set its own tariffs on goods not destined for Europe, while obviating the need for checks on the Irish border via a high-alignment with the EU’S single market for goods.

By this Mrs May hoped to retain an independent trade policy while avoiding damaging the Good Friday Agreement or creating the need for a goods border in the Irish Sea that split the UK. But Brexiteers rejected this. They say it would lead us to a state of abject vassalage in Europe and deprive Brexit Britain of the freedom to strike independent trade deals. And all said and done, they are not wrong. The problem is that their option, a zerotariff FTA coupled with “maximum facilitation” of customs arrangements, does not fix the Irish question. Why? Because the UK government has agreed “no infrastructure” at a border that runs entirely through Sinn Fein-controlled constituencies; there is no border in the world that exempts small business; and the EU won’t allow a legal lacuna in its external border.

Michel Barnier set this out with ruthless clarity in Ireland this week. So if the UK wants to diverge, as the Brexiteers demand, logic requires a goods border in the Irish Sea. Mr Barnier suggested this, but the DUP and indeed the Conservatives rightly reject this as unacceptable.

But these are the choices. The Brexit ratchet tightens day by day. And the decisions to be made must be based on facts, not wishful thinking.