AND now the end is near, as Sinatra put it in his truly dreadful adaptation of a lousy French song called Comme d’habitude, now the favoured party piece of a certain sort of karaoke singer. As of last night, there are fewer than 50 days to go till, well, who knows what?

Not Theresa May, off to Brussels again – though not, we were told, to suggest an actual change to her withdrawal agreement that would make it possible to get it through the Commons, but merely to tell the EU that there will have to be some sort of change, because nobody will put up with the backstop as it is. I suspect the Prime Minister of being the sort of woman who might choose I Will Survive when roped into the karaoke, but no one can deny that she’s done it her way. Even though her way has created most of the problems.

But however traumatic and alarming the road to Brexit has been, you’ve got to give this political drama credit for retaining the ability to surprise. Of all the possible outcomes (many of them still on the table, or as some people have argued in the case of no deal, actually being the table itself), the one which never occurred to me was that Jeremy Corbyn would start talking some sort of sense.

I don’t want to overstate the case, obviously. The letter that the Labour leader sent to the Prime Minister still describes a kind of Brexit which I don’t like or want. But I think we’ve all accepted that we’re none of us going to get what we want, and Mr Corbyn – in his own way just as stubborn as Mrs May – has at least managed to do what she has not, and drop some of his pet preconceptions of what Brexit has to be.

There’s the small point that the Labour Party’s previous position, set out in six tests of spectacularly vague aspiration, not to mention downright fantasy, was even more ludicrous than Mrs May’s vision. Indeed, the only one of those tests which had any detail – that we retain absolutely every benefit of EU membership, but leave anyway – was not just fantastic but by its own definition literally impossible.

The same can’t be said of the new version of Labour policy, though, as is also true of the Tories, it’s never entirely clear whether this is actually policy or merely what think-tanks like to call “a contribution to the debate”. But it is actually a contribution; and a reasonable and constructive one, at that.

Instead of the six tests, there are five demands, simply described and perfectly cogent: a permanent UK-wide customs union; alignment with the single market; alignment with EU rights and protections; participation in EU agencies and close co-operation on security, including the European Arrest Warrant. The remarkable thing about the letter detailing these (which even concedes that Mr Corbyn doesn’t expect to get absolutely everything) is not just that it’s thoroughly serious, but that it is quite reasonable to think of all those demands as achievable. In fact, though it doesn’t describe them in terms of the EEA, the five demands are very similar to the Norway + or Common Market 2.0 solutions which have been suggested by the likes of Labour’s Stephen Kinnock and the Tories’ Nick Boles.

There are several advantages, of which the main ones are that it’s a kind of off-the-shelf solution which the EU has already given other countries, that it delivers Brexit without throwing trade and business into chaos, and that it probably stands as good a chance as anything of getting through the Commons.

I repeat that I don’t like it myself. If you were to choose between being in a customs union or the single market, you’d go for the latter. A permanent customs union, without EU membership, would put us in the same position as Turkey, unable to strike independent trade deals with third countries, but compelled to accept the terms of deals the EU negotiates with other nations, without any say in formulating them, and with those third countries under no obligation to reciprocate.

But as Mr Corbyn’s letter points out, EU leaders have already said that such changes to the Political Declaration are possible, if there are changes to Mrs May’s red lines (which are what have caused all the trouble and which have no basis or rationale of any kind, except that she just decided on them).

The fact that it would involve the Prime Minister backing down at all is one good reason for thinking that this Labour plan probably won’t happen. Even so, the party’s new position is a significant development. Even if I don’t think it’s a sensible plan, it’s at least not a nonsensical one.

The other thing that makes it significant is that Mr Corbyn has nailed his colours to the mast. He’s clarified that Labour remains committed (as it was in its manifesto, after all) to delivering Brexit, though a fairly soft version of it. That may not be the majority view of Labour members, or even MPs, but at least it lets the electorate know the party’s stance.

Last week, I thought that the only realistic option that avoided a no deal Brexit was a rewording of Mrs May’s withdrawal agreement. If – a huge if – some substantial alteration to it can be negotiated, it still seems much the most likely outcome. That’s mainly, of course, because the Prime Minister is not the kind of person who has regrets, even though they ought to be too many to mention. But the shift in Labour’s position revives the outside possibility that something akin to an EEA solution could be got through the Commons.

It’s also, if there were anyone out there still flogging the People’s Vote horse, a fairly bald statement that, as far as the Labour leader is concerned, that particular nag has been shot and sent to the knacker’s yard. Whether this new stance is in the Labour Party’s best electoral interests, or stands any realistic chance of coming about, matters less than the fact that at last someone has produced a relatively sensible proposal, even if it’s one I don’t much like. I’m just amazed that it turned out to be Mr Corbyn.

Read more: May's demand rejected