Just suppose May fails to get a deal, or her proposed Withdrawal Agreement (WA) fails to be passed by a majority of MPs. Suppose for some reason this results in an election that Labour wins. Labour have not pledged to have a referendum in those circumstances, and I think this is more than triangulation. It is increasingly clear that the Labour leadership want to do a Brexit deal with the EU.
I think it is also becoming clear that this deal will be essentially Brexit in Name Only (BINO): we stay in the Customs Union and Single Market. The Labour leadership will want assurances on nationalisation as well as other elements in their manifesto, and the EU will give the (substantial) assurances it can without changing EU policy in any way. Labour will I suspect also come back with a package on Freedom of Movement that involves enforcing the existing rules (EU nationals have to find work within 3 months) and any other sweeteners the EU care to throw them. That all adds up to BINO.
The key characteristic of BINO (which is what gives it its name) is that everything it does can be achieved by staying in the EU. As far as any sweetners are concerned, it is plausible that the UK is more likely to get those being part of the EU than being outside it. All that BINO achieves is to give up a direct say in how the EU evolves, and giving that up without any compensation cannot be in the national interest.
So why would Labour bother to do this? The answer I think is that they want to keep the minority of Labour voters who still favour Leave voting Labour. When the leadership says that they must respect the referendum result they do not really mean that it is undemocratic to hold another referendum: they are not that stupid. What they mean is that they do not want to antagonise Labour Leavers. In addition they believe that BINO with sweeteners would convince enough Labour Leavers that Labour had got the job done, and these voters would not worry too much about the details.
Before getting on to whether they are right, it is worthwhile noting that this has nothing to do with the Labour leadership being Leavers at heart. In a smart tactical move, Corbyn in his closing conference speech said he would back a WA that came from May if she delivered “a deal that includes a customs union and no hard border in Ireland, if you protect jobs, people’s rights at work and environmental and consumer standards - then we will support that sensible deal.” The inclusion of Ireland and protecting jobs means in practice staying in the Single Market. You just wouldn’t make that pledge if you wanted Lexit.
Of course exactly the same question arises for Theresa May and the Conservatives, if as I suspect the EU is not prepared to extend the backstop to the UK and so BINO is the only deal that avoids an Irish border anywhere.
So would BINO heal the wounds opened up by the original referendum or would it satisfy no one? A positive argument would start by suggesting that most Remainers will not mind losing any say in the EU, because they would be so relieved that we had avoided a hard Brexit. The people who should be worried about this loss of sovereignty are Leavers, but they will be more concerned with actually leaving. And both groups will be relieved it is all over.
The argument against is that BINO is clearly inferior with being a member of the EU, so Remainers will know we have done something that is clearly nonsensical. Leavers on the other hand will be convinced (by the Brexit press in particular) that this result is a sham Brexit, and therefore a betrayal of the original referendum, which is roughly how May herself has described it. As time goes on both sides will forget that the government was fulfilling a democratic mandate, and instead blame it for agreeing a Brexit that nobody likes.
I don’t see how it is possible to know which of these outcomes will come to pass, which in turn means a government that enacts Brexit is risking a lot. Of course politicians are used to taking risks, but these risks normally involve trying to achieve something they think will do the country, or part of it, some good. It is somewhat novel to take risks to achieve something that in itself does nothing but reduce the country’s influence and sovereignty.