Will Boris Johnson end up dumping the ERG and DUP? asks Robert Peston

Don’t laugh, but Boris Johnson would genuinely prefer a Brexit deal to no deal.

And that should make Northern Ireland’s DUP and the Brexiter purists in the Tories’ European Research Group very nervous indeed.

Because the EU has made it clear that it thinks a deal could be done if the backstop arrangements, designed to keep open the border in the island of Ireland, was remade as a Northern-Ireland only backstop rather than a hybrid of customs union for the whole UK and some NI-only arrangements.

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There is evidence of Johnson moving in that direction, with his initial concession that there could be a single market for agriculture for the Republic and Northern Ireland that would be bossed by Brussels.

Which to some unionists will look like the thin end of the wedge towards that regulatory border in the Irish Sea they regard as toxic.

And which to ERG Brexiter fundamentalists is redolent of the PM failing to do as they thought they had instructed him, namely to rip up the whole of Theresa May’s Withdrawal Agreement.

To be clear, we are weeks away from what would be seen by Arlene Foster, Steve Baker and their allies as the great betrayal - if it ever comes.

But they know their leverage to stop it has vanished. Because the very worst they can threaten is to bring down the government and force a general election.

To which Boris Johnson would presumably respond with a Beano or Pericles version of “bring it on” and “make my day”.