Corbyn is wrong about most issues but right about the Brexit deal on Northern Ireland

It is not merely the fact that he has embraced views that would be economically disastrous, as they have been in countries round the world, including recently Venezuela, or even the fact that he has been a supporter of terrorism, which is particularly repugnant here.

Lots of politicians, some of them great ones, have held thoroughly unacceptable views earlier in their lives and abandoned them.

It is more the fact that the Labour leader has changed none of these views at all, it seems. That he invited republicans to Downing Street weeks after the IRA bombed the cabinet of an elected government, and has never resiled from that stance, is telling about him.

Yet it is not good enough for Boris Johnson to cite that past sympathy for the IRA in response to Mr Corbyn in the House of Commons yesterday, when he referred to Northern Ireland having been thrown ‘under a bus’.

Mr Corbyn pointed out Mr Johnson’s remarks to the DUP conference last year about never accepting regulatory and custom checks in the Irish Sea, and now having accepted them. It is a shameless u-turn, and all the more unforgivable in someone who paraded himself as a unionist.

Here in Northern Ireland, supporters of the Union are struggling to comprehend the scale of what has happened, and the abject failure of London to stand up to Dublin (as it never does on any issue).

It is nothing less than a betrayal by the prime minister’s own previous words. It is he who set the bar.

How can cross-border relations resume now that the Irish government has behaved in this way? How can Stormont talks resume under Julian Smith, with Simon Coveney yet again making clear that he has joint control of the process?

And how can the DUP say that the confidence and supply deal is still intact?