Pity Olly Robbins and Sabine Weyand who are as we speak negotiating a Brexit deal for their respective bosses, Theresa May and the EU27.

Because following the resignation of Jo Johnson, it is now clearer than ever that the deal they will probably agree this weekend, to be put to the Cabinet on Monday (or at the very latest on Tuesday), will be rejected by Parliament.

They are straining every one of their intellectual sinews to reach an agreement that is almost impossible given the ideological gulf between them on how to keep open the border between Northern Ireland and the Republic of Ireland.

And when they succeed through the application of sophistry on a Herculean scale, what then?

British MPs will spit on the fruits of their toil and then incinerate it,

As an exercise in futility it is Pinteresque.

Their putative compact is detested by Leavers and Remainers for almost identical reasons - they see it as giving the EU too much control over our future economic destiny.

What the arch Brexiter Jacob Rees-Mogg described as the flaws in the expected deal on my programme on Wednesday was almost identical to the critique of arch Remainer Johnson in his resignation statement yesterday.

They both employ the archaic term "vassalage" to depict May's arrangement with the EU - a shorthand for being forced to follow EU rules for the standards to be followed by manufacturing and the City, in order to secure inferior access to the EU's single market to that we enjoy at the the moment.

And they make common cause with the unionists of the DUP, without whose votes May's party is in a permanent state of minority within parliament: the DUP shares the general concerns of the Brexiters, and overlay that with their hatred of the Ireland backstop that would forever keep open the theoretical possibility of a new border being drawn between Great Britain and Northern Ireland.

And just in case you - or May - harbour residual hopes that Labour will bail her out (which is not completely bonkers following Corbyn's statement yesterday that he can't "stop" Brexit), I can tell you now categorically that it won't.

Labour will vote against the deal. "It's impossible for us to vote for a May deal" a very influential member of the party tells me.

So she'll lose when the so-called meaningful vote is put to MPs, probably in early December.

And before then there will probably be other resignations from her ministerial team: Remainer and Brexiter ministers tell me they won't quit like Johnson before they've read the small print on May's Brexit; but they reserve the right to do so as soon as they've got it.

Where are we heading?

The destination is constitutional crisis, where legislature will be in irreconcilable conflict with executive, Commons at odds with PM and her cabinet.

In the end MPs will get their way - because ultimately power resides with them. But what you may have noticed is that although MPs are united on hating May's Brexit, they are not on what comes after, which could be referendum, or general election, or Brexit renegotiation, or negotiation to join the European Economic Area, or no-deal Brexit (there are supporters in parliament for each of these outcomes).

It's the mother of all flippin' messes.

This article originally appeared on Robert Peston’s Facebook page