Theresa May ran away from a vote on a customs union, but she can’t avoid her defeat for ever

This is going to matter eventually, because there will be binding votes on the same question

It’s called leadership by running away. The prime minister has just been defeated in parliament on the question of whether Britain should be in a customs union with the EU after Brexit. The government whips failed to object, so the motion in favour of a customs union was carried without a vote.

If Julian Smith, the Conservative chief whip, had tried to mobilise a vote for the government’s policy, which is not to be in a customs union, the result would have been close, but it would have produced the same result. Thirteen Tory MPs have now expressed support for a customs union – Dominic Grieve added his voice to the cause in this afternoon’s debate – which is enough to wipe out May’s slim working majority, even taking into account the few Labour hard Brexiteers who might support the government.

So Smith deployed the tactic of abstaining and trying to pretend the vote doesn’t matter. This device became increasingly common when David Cameron was prime minister as a way of trying to minimise the embarrassment of defeat.

Previously, the convention had been that, if the government lost a vote, a minister would come to the House of Commons to explain what it intended to do about it. Cameron and his chief whips realised that, if they simply ignored defeats on opposition or backbench motions, there was nothing anyone could do about it.

So now MPs are well aware of the difference between binding and non-binding votes. The first kind are legislation, such as the act that allowed the government to trigger article 50, or an antiquated procedure called a humble address, which is how Labour forced David Davis to publish his Brexit assessments.Today’s vote, on a motion tabled by a group of backbenchers led by Yvette Cooper (Labour) and Nicky Morgan (Tory), was not binding.

Some Labour MPs are heated about this affront to democracy: how dare the government simply ignore inconvenient votes in the Commons? Today Chris Leslie, Labour MP for Nottingham East, indignantly demanded a government response, but he isn’t going to get one.

However, the government cannot brush its defeat aside altogether, because it confirmed that there is a majority in the Commons in favour of a customs union. This is going to matter eventually, because there will be binding votes on the same question.

Hence the air of anticipation already building over an amendment tabled by Chuka Umunna and Anna Soubry, another cross-party alliance, to the Trade and Customs Bill. That vote could be held next month or in June, although it is unclear what effect it would have if the amendment is carried.

So it may not be until the end of the year that the question of a customs union is finally decided. The government has been forced – by a rebellion of Tory soft-Brexiteer MPs in December – to hold what they call a “meaningful vote” on the Brexit deal when it has been negotiated. At that point, parliament could vote to try to amend the deal to include a customs union.

It is unclear what would happen then. The EU27 would be willing to make the change, because it would make trade easier for them, and would probably already have a draft section of the treaty ready for approval. But Theresa May could insist that Britain must have a free hand to negotiate its own trade deals, which would be restricted by a customs union. If she refused to accept it, she could threaten to take Britain out of the EU without a Brexit deal at all.

I can’t see that happening. As Amber Rudd reminded us today, by failing to rule out staying in “a” customs union, there are alternative leaders who could be prime minister who would accept the will of the House of Commons. So May is likely to compromise and accept a partial customs union, even if she calls it something else. The Tory hard Brexiteers might try to replace her with someone else, but I doubt that they would succeed.

Despite today’s cynical manoeuvre in the Commons, parliamentary democracy will probably win out in the end.