Henry Newman is Director of Open Europe.

Theresa May has managed to get to “sufficient progress” partly by kicking the can down the road on a variety of issues – above all on the question of the Irish border. Of course, there’s a healthy EU tradition of can-kicking (see, for example, the Euro crisis in its many incarnations). But, as my colleague Stephen Booth has argued, at some point political chickens will come home to roost. The Cabinet will need to decide on whether we will be more like Canada or more like Norway. A discussion on that is scheduled for next week. My guess is that, if the Government doesn’t agree that the UK will have the ability to decide its own future regulation, there will be the most almighty bust-up. But for now, May has found a path through, assuming this week’s European Council meeting goes smoothly.

Meanwhile, the muddle on the Labour benches shows little sign of abating. I’ve written before about Labour’s Brexit policy hokey-cokey: in the Single Market and Customs Union, out the Single Market and Customs Union, and then shaking it all about. But the mud in the water shows little sign of clearing. The shadow front bench are descending into double speak. On Sunday, Sir Keir Starmer refused to answer Andrew Marr’s gentle probing by saying that: “my problem is I always get very technical”. But the problem with Labour’s position is actually that no one can explain what it really is.

Labour’s position seems to be that – after the transition – they want to keep the benefits of the Single Market and Customs Union, but not the structures. This is pretty much the definition of cake having and eating. Their idea is that the EU will, thanks to the brilliance of their negotiation skills perhaps, accept a relaxation of the rules of both institutions. This is palpably ridiculous but, so far, their arguments have escaped serious scrutiny.

In 2015, David Cameron won a surprise majority. He went to Brussels asking to renegotiate Britain’s membership of the EU. He was assisted by talented advisers (including Dan Korski and Mats Persson) and able officials. Cameron’s ‘deal’ included some real changes but nothing that really dealt with public concerns over free movement. As a result, it wasn’t given a particularly significant role by the Remain campaign. The overall package was then flatly rejected by the British people in the 2016 referendum. Labour’s position is that they will get a better renegotiation than Cameron’s but from outside the EU. How?

What Single Market rules will the Labour Party seek to re-negotiate? From the EU’s point of view, the Single Market is underpinned by acceptance of the four freedoms. For the renegotiation to deliver something which might meet with public approval, Labour presumably would have to get the EU to accept an ‘opt-out’ or limit on free movement. That, of course, is something which EU leaders have repeatedly refused to consider. At every opportunity, EU leaders and key European politicians have rejected cherry-picking. That’s why May has called the EU’s bluff by accepting that we won’t cherry-pick – we will leave the Single Market.

What of the Customs Union? Barry Gardiner, Shadow Trade Secretary, confirmed to me that the UK will “cease to be a member of THE customs union when we leave the EU” [his emphasis]. That’s correct. And it’s helpfully precise as, when discussing things Customs Union, the definite article marking the EU’s Customs Union is often omitted, leading to endless confusion. Monaco is the only non-EU member in the EU’s Customs Union. To put this another way – even Norway, Iceland and Lichtenstein, the EEA states which are closest to the EU, are outside the EU’s Customs Union. With the exception of the microstates of Andorra and San Marino, only Turkey has established a partial customs union with the EU’s Customs Union.

My assumption was that Labour’s position was to establish a Turkey-style Customs Union with the EU. But Gardiner explicitly rejected “a customs union AGREEMENT with EU, like Turkey has” because it “would give EU power to decide our tariffs & quotas with 3rd countries. We’d be forced to liberalise our market but have no reciprocal access to theirs”. He’s right, of course, but that’s why we need to give up on the idea of a Customs Union, as Open Europe has argued.

Gardiner then suggested that “Post transition period Labour wishes to secure the BENEFITS of both SM & CU [Single Market and Customs Union] but is not committed to existing structures which remain options on the table”. So Labour neither wants to be in a Customs Union nor the Customs Union, but doesn’t want to take either option off the table. Well, that’s clear.

The reality seems to be that Labour is trying to square an impossible position. The idea of renegotiating the Single Market and Customs Union rules, as a non-EU member, is a chimera. But it’s designed to paper over the deep ideological divides within the Party. Senior Labour figures remain fundamentally unreconciled to the referendum. Of course, it’s true that some Tories are less than delighted by the referendum, too, but only a very few actively seek to undermine the manifesto position of leaving the Single Market and Customs Union. And following Theresa May’s success on Friday, MPs and leading figures from all wings of the Party have heaped praise on the Prime Minister.

Despite Labour’s manifesto commitments, Blairite figures continue openly to suggest that the UK could and perhaps will never ultimately leave the EU. Chuka Umunna is raising money for an ‘Exit from Brexit’. Starmer has privately told mutual acquaintances of his intention to slowly shift Labour’s position in this direction. Alison McGovern disingenuously suggests that the question of Single Market membership was not addressed during the referendum when it was answered by the campaign leaders on both sides.

Structures do matter when it comes to international organisations. You’re either in the Single Market or you’re not. You’re either in a Customs Union or you’re not. The Conservative Party ought to spend more time exposing these divisions in Labour and less time arguing with itself.