In case you were in any doubt, there is zero chance of Labour and Jeremy Corbyn agreeing a Brexit deal with the Prime Minister, given that its central element is a pledge to keep the UK in the customs union till the next general election.

The point is that Labour’s main criticism of Theresa May’s Brexit plan is that it is “blind”, that it makes gives no promises or commitments about the UK’s future relationship with the EU.

And a pledge to keep the UK in the EU’s customs union only till 2022 would not turn blindness into perfect foresight.

So she needs to commit to keeping the UK in the CU to stand any chance of an entente with Labour.

Why won’t she offer that?

Because to do so would split her party down the middle, and cause maximum chaos for her.

And why will Corbyn refuse to compromise and continue to press for permanent membership of a customs union?

Because to do so would split May’s party down the middle, and cause maximum chaos for her.

So talks between government and Labour will fail.

But they will last just till it becomes chronically embarrassing for each party that the fiction of a possible cross-party Brexit pact renders meaningless and fatuous all their campaigning in the EU elections - which probably means the talks collapse at the end of the week.