"Which Union?"

That question needs to be put to a referendum in Scotland, to a referendum in Northern Ireland, and to a referendum in Gibraltar.

In Scotland, the options would be the United Kingdom outside (or, at any rate, nominally planning to leave) the European Union, and independence with a view to seeking EU membership.

In Northern Ireland, the options would be the United Kingdom outside (or, at any rate, nominally planning to leave) the European Union, and incorporation into the EU member state of the Irish Republic, assuming that it would be willing to take Northern Ireland, which is very far from clearly the case.

And in Gibraltar, the options would incorporation into the United Kingdom outside (or, at any rate, nominally planning to leave) the European Union, and becoming an autonomous community of the EU member state of Spain.

In no case would there be any third option, and in all three cases the result would be final.

All of this needs to happen this year.

Although of course it does assume that the United Kingdom has the slightest intention of ever leaving the European Union.

We all know about "transitional periods".