Once upon a time, the Labour party believed the road to Downing Street ran through Scotland. This was, it is true, a long, long, time ago. By which I mean it was what the Labour party’s leadership believed in the summer of 2017. A different time; a simpler time.

Then Labour people were fond of claiming that 18 of Labour’s top sixty or so target seats were north of the border. Win them and Labour would be back in business and back in office. You don’t hear very much of that sort of thing anymore.

And with good reason for the Labour party in Scotland is a husk of what it used to be. It lost its empire years ago and has still not found a role. It occupies the position previously taken by the Scottish Conservative and Unionist party: an object of occasional, pitying, fascination, not a serious political project.

Granted, Labour did enjoy a bounce in 2017. The party holds seven Scottish seats now whereas in 2015, amidst the SNP tidal wave, it was reduced to just a single representative: Ian Murray in Edinburgh South. This being the Labour party, Murray – who has the largest majority in Scotland – was the only Labour MP subjected to an attempt at deselecting him. There being a sad shortage of Marxists in Morningside, this coup, launched by Unite, ended in predictable failure but its significance lay in the attempt.

Perhaps Labour can hold its Scottish territory and perhaps, just perhaps, the possibility of a socialist government in London will persuade some Scottish voters to back Labour in marginal seats such as Lanark and Hamilton East (the closest three-way marginal in the UK). It seems worth noting, however, that the party leadership is not behaving in ways you might expect it to if you believed this were actually the case.

Hence, on the first day of this long election campaign and before it has even officially begun, Andy McDonald, the shadow transport secretary of whom most of you will never have heard, told the BBC’s Politics Live programme that “Labour won’t stand in the way of a second independence referendum”. As a number of journalists noted, that is actually Labour’s official policy even if, inconveniently, it is not at all the policy of the Scottish Labour party.

John McDonnell, whatever his other shortcomings, can at least count. A Labour majority seems improbable right now. So if Labour is going to make it to Downing Street it will require the support – albeit perhaps on a confidence and supply basis – of other parties. The SNP are both the largest and the most obvious candidate to provide that.

Their price is simple too: agreement that there should be a new referendum on Scottish independence. Sometimes, it is true, Labour suggest this should not be accommodated in the “early years” of a Labour government but that’s a line offering the SNP everything they want. It’s not going to hold and nor is it even designed to hold.

Why would it? I am convinced Corbyn is intensely relaxed about Scottish independence and the break-up of the United Kingdom because the majority of people in Scotland who agree with Corbyn on most things are so relaxed about independence they voted for it in 2014. I have no doubt whatsoever Corbyn would have done so too had he been living in Scotland five years ago.

Scottish Labour, however, would prefer not to be undermined by their own head office in this fashion. They are wholly capable of undermining themselves without this interference from London. Officially, the line is that a second referendum is a Very Bad Thing, up with which Scottish Labour shall not put. But, really, who are you going to believe: the branch office or party headquarters? First they hamstring you; then they kneecap you.

From which it follows that the Labour party in England believes a vote for the SNP is, in the end, almost a proxy vote for a Labour government. When the votes are counted it doesn’t make very much difference if they are cast for Labour candidates or SNP representatives. The end effect is broadly similar: votes in the House of Commons to make Jeremy Corbyn prime minister.

Naturally, the Scottish Conservatives will be delighted by this. It allows them to play their best card: only the Tories will stand up for Britain. Some things are more important than Brexit and Unionism is one of them. So if you value the UK, you should vote Tory even if you dislike Brexit intensely or think it a blunder of historic dimensions. (And you should do so even if you suspect, with some reason, that Unionism’s flame is flickering south of the border). There may be more mileage in this than today’s received wisdom would have you believe.

For Scottish Labour, however, this is an invitation to be squeezed still further. If you dislike Brexit, why vote for Labour when you can back the SNP? If you dislike independence, why vote Labour when you can back the Tories? The least-populated quadrant of Scottish opinion is that which is relaxed about Brexit and relaxed about independence yet, puzzlingly, this appears to be the place in which Labour has put itself.

So these promise, I think, to be another long and lonely six weeks for the Scottish Labour party. The UK leadership plainly considers Scottish Labour disposable; a sacrifice worth making if that’s the price of power. But it is a reminder, too, that this Scottish election will be a very different creature to the election fought elsewhere in the realm.