Some Scottish Labour back-room boys are punting the idea that in the event of a Labour minority government the SNP will be stuck because that party is already committed to blocking the Tories. This idea is so hollow and frankly daft that it’s disappointing to see it repeated today without any interrogation by normally-thoughtful columnists like The Guardian’s Martin Kettle. Kettle actually adds that a Labour government would find it more convenient to do deals with the Tories most of the time anyway, without apparently realising that this line will make SNP politicians belly-laugh because of course Labour and the Tories acting together to block ‘progressive’ SNP proposals is EXACTLY what will drive up SNP support in Scotland yet further.

But, leaving that hilarious misreading of the Scottish dimension aside, when you’re in opposition and put down amendments or inspired private member’s bills, you don’t get to prevent other parties voting for your ‘good ideas’. Scottish voters aren’t daft – they do understand this. No-one in Scotland would equate the Tories piling-in opportunistically behind legislative proposals from the SNP over the next few years with the SNP enabling a Tory government next week.

So the obvious thing for the SNP, which has an overall majority at the Scottish parliament, to do would be work on ‘progressive’ measures which the Tories can support. For example, it’d be easy enough for the SNP to inspire organic campaigns in Scotland which led to ‘progressive’ legislation there, then put down related proposals at Westminster which Labour couldn’t support. Think the Tories in opposition wouldn’t support free things for the elderly or unaffordable increases in funding for, say, children’s mental health?

Or think such money would have to first be found in Scotland? Of course it wouldn’t. The SNP could demand vast increases in welfare at UK taxpayers expense, for example. But even on devolved issues, most people in Scotland understand that the Scottish block grant comes from decisions at the UK parliament. Indeed, this has always been the argument used by the unionist parties for Scots MPs voting on devolved issues. It’d be perfectly credible in Scotland for the SNP to put down Health legislation at Holyrood which required only a very modest budget uplift there, with a vast increase in funding being dependent upon decisions at Westminster.

For the SNP, it’d simply be a question of identifying areas where they can say a measure is progressive (like free prescriptions for all) which is from a Labour perspective actually regressive (because giving everyone something free doesn’t take account of means or need) or simply unaffordable. Scots have already bought fully into the right-of-centre notion that giving free things to everyone is progressive. A new Tory leader would find it expedient, convenient and fun to jump in behind such ‘progressive’ measures while his/her supporters in the shires would understand exactly who would really benefit.

As they’ve done in Scotland, the SNP will be mainly thoroughly reasonable at Westminster. They’ll support sensible government legislation where Scots would object if they didn’t, and they’ll abstain from anything they don’t want to be tainted with. If they hold the balance of power, at critical moments – like shortly before next year’s Scottish elections – they’ll put ‘progressive’ amendments down which will get the whole opposition’s support and they’ll break key bits of government legislation. Once they’ve done that a few times over the years, they’ll break the government itself unless it accedes to another referendum.

For Kettle and the backroom boys, the SNP fears 1979 too much for a threat to take down another labour government to be taken seriously. But do you know why they’re wrong? They’re wrong because many Scots will vote SNP next week truly believing that Labour and the Tories are ‘all the same’. A few years of a Labour government knocking back ‘progressive’ SNP legislation would convince many of those who don’t buy that already that the SNP is right after all. In the 80s and 90s and 00s, most Scot’s visceral (to the point of irrationality) hatred of the Tories led them to vote Labour. Now the visceral hatred of many Scots extends to Labour too.

Faced with an all-conquering SNP in Scotland in its third successive Scottish administration and holding most of Scotland’s Westminster seats, an SNP which has proposed only ‘progressive’ (from a Scottish perspective) legislation throughout the first 2 or 3 years of Labour government and which Labour and the Tories have come together to knock back, Ed Miliband would be given a choice by the SNP. Accede to another referendum and serve out a near full term – or kiss goodbye to government early.

For the Tories, who’d have long given up on Scotland, supporting the SNP threat and knocking down Labour – with some ruse – would be a a no-brainer. For prime minister Miliband, facing the loss of few MPs in a rampantly nationalist Scotland, the same would apply.

In Kettle’s case, he oddly goes on to say that – perhaps because of this stymie-ing, it’s not clear – it would be ‘brave’ of the SNP leader, Nicola Sturgeon, to work with Labour constructively.