What I love about covering the Labour Party is that if you live long enough, every possible position will be adopted by every available faction. 30 pro-European grandees, ranging from the parliamentary party to the mayors of the cities of Liverpool and Manchester to, have written to the chair of the party’s ruling national executive committee, calling for party members to be consulted on the party’s European strategy.

Although the ideological make-up of the list is not exclusively drawn from those you could fairly call “Blairite”, it is fair to say that it is not a list of people who, in the main, have been particularly excited about opening up the party’s policymaking processes to ordinary members, although there are exceptions. Equally, of course, the Labour leadership has a longstanding history of support for consulting the party membership beyond the confines of party conference, and polled members on the question of whether or not to bomb Syria.

The problem Labour's pro-Europeans have is that they have the numbers to override the government's majority as far as retaining the single market and customs union goes on paper. That is to say, the number of willing Conservative dissidents is enough to overcome the Tory-DUP majority. Unfortunately, it's not enough to overcome the votes of the seven Labour leavers and the Tory-DUP majority.

The difficulty is, the pro-Europeans were right the first time. No vote – not of the country, not of the Labour membership, not of Parliament – can make leaving the single market and customs union the right approach for the United Kingdom. No vote – not of the country, not of Parliament, and not of the Labour membership – can make it the wrong approach for the country either. That’s not how economics or policymaking works.

Ten million people voted for the Conservative plan to close the deficit in 2010 and 11 million did so in 2015. In both cases, that plan turned out to be unrealistic and unachievable. The last election narrowly repudiated a plan to take the East Coast rail franchise back into public hands but now the demands of running that franchise may mean it happens anyway. Votes can change a lot of things but they can’t change facts.

The only question that ought to matter for MPs is not what the party whip says, not what they think will happen to them at the next election, and not what their membership says, but whether staying in the customs union and single market is the right approach or not. And the problem for pro-Europeans is that a critical mass of Labour's Brexiteers think that it isn't.