The Commons can vote in any way that it wishes.  It could declare itself in favour of five year olds having the vote, or back building a golden statue of Kim Il Jong in Parliament Square or, less improbably, declare itself opposed to no deal with the EU, if such is the outcome of the Brexit talks.  Let us ponder what might happen if it did.

Such a vote would show the Government what MPs were against.  It would be unlikely to spell out what they were for.  The Commons does not have the capacity to draw up an a la carte deal in detail and present it to Ministers.  It could, however, pick a table d’hote solution off the table, such as EEA or EFTA membership, and recommend it to the Government.  This would be improbable, if only because neither is fully compatible with “taking back control”, or allows for a proper system of EU migration control.  Labour MPs in northern and midlands constituencies would be very wary of taking such a route.  So in all likelihood would be most Conservative MPs.  Only 101 MPs voted for Britain to stay in the Single Market when they last had a chance to do so. The odds of a majority backing such a move in future look long.  Furthermore, Tory MPs would kick up against voting for any motion tabled by Jeremy Corbyn’s front bench, so another means of holding a vote against no deal would doubtless be sought.

The more one thinks about it, the more one comes to see that such a vote would be a combination of different motives.  Remain-backing MPs would want Britain to remain in the EU.  Others would favour a Norwegian-style settlement, with Britain remaining in the Single Market.  Others still would favour staying in the Customs Union as well or instead.  The DUP would oppose a hard border.  Corbyn would want to destabilise the Government.  Labour would surely shy away from saying that Ministers should hand over billions more pounds to the EU – which would scarcely play well with voters – and stick to generalities about how the Government had messed up the talks.  Few MPs would want to declare that the UK should abandon the prospect of controlling EU immigration.

In these circumstances, Theresa May, who we must assume would still be Prime Minister, would have three courses of action open to her.  The first would be to ignore such a vote.  This would presumably not be tenable, at least for long.  The second would be to fly back to Brussels to explain to our EU interlocutors that the Commons had declared itself against no deal, but not expressed a clear view about what a deal should consist of.  She could make footling changes to the Government’s negotiating position.  She could make major ones.  She could seek to drag the new talks out.  In these circumstances, presumably, there would be a hue and cry for a general election.

But this to-and-fro would take place with the clock running down to Britain’s exit from the EU at the end of March 2019.  The alternative to leaving the EU with no deal, as formally rejected by the Commons would thus be…leaving the EU with no deal.  (There is a parallel here with that other hypothesised Parliamentary vote – namely, one against a deal, in which the alternative to leaving the EU with that deal would again be leaving the EU with no deal.)

The Commons could seek a way through any such impasse by calling for the Article 50 talks to be extended.  It is not at all certain that our EU interlocutors would agree to such a move.  It is also very unlikely that this Conservative Government would, or could survive long if it did.  Furthermore, Corbyn and his front bench would have to think very carefully before endorsing such a move.  This is because extending the talks would mean prolonging Britain’s EU membership, which would in turn fly in the face of last year’s referendum verdict.  (It would also shift into the middle distance a general election that they might win.)  A more efficient means of creating some new UKIP-type movement, with Nigel Farage freed from the irrelevance that threatens to confine him, is hard to imagine.

Which returns one to May’s third option in the event of the Commons preparing to vote against no deal.  It would be to point out that provision for this outcome was written into the manifesto on which every Conservative MP stood. (“The negotiations will undoubtedly be tough, and there will be give and take on both sides, but we continue to believe that no deal is better than a bad deal for the UK.”)  In these circumstances, she would be entitled to declare such a vote to be one of confidence in the Government.  Any Tory MP goes through the lobbies with Corbyn would thus be deprived of the whip.  In the event of the Government falling, he or she would thus be ineligible to stand as a Tory candidate in the general election that would follow.

Finally, the current discussion about a Commons vote against no deal is not taking place in a vacuum.  Rather, it has been triggered by the tabling of amendments to the EU Withdrawal Bill which would require a vote if a deal is not agreed.  If such an amendment passes, the Commons will have degraded one of the strongest negotiating gambits that a Government can hold: namely, its freedom to walk away from the table if it doesn’t like what is on offer.  This is the posture to which John McDonnell committed Labour yesterday – a development that Tory MPs may like to ponder.  Unpatriotic is not a term that we use lightly, but it is difficult to describe it in any other way.