“Let me be clear – I want to be judged on this. If you are not, as First Minister, prepared to put your neck on the line on the education of our young people then what are you prepared to? It really matters.”

Well, you can’t say fairer than that, Mrs Sturgeon. You want to be judged on the success of your education policy. That’s understandable, with education traditionally being an iconic preoccupation with Scots. So, let’s see, how is that playing for you…?

Er – there’s some data here from the Programme for International Student Assessment (PISA) that seems a little – uh – incongruous… Actually, Nicola, are you sure you don’t want to change what you want to be judged on from education to, say, ping-pong or performance on the bagpipes? Okay.

Well, it seems that between 2006, the last year before the SNP came to power, and 2015 Scotland’s ranking has declined slightly from 11th to 23rd for reading – probably just a 10-year glitch – and from 11th to 24th for maths, which is only a little worse. The good news is, for science, the slippage was only from 10th to 19th: you would have to be a carping nitpicker (or a Scottish parent) to complain about that.

You should fight your corner, First Minister, in this election campaign and explain to Scottish voters that there is no shame in being outperformed by Slovenia – a highly intellectual nation – and that Scotland can also proudly claim to be doing as well as Latvia. It should further be borne in mind that Scotland labours under the handicap of being shackled to England, a connection that has weakened her sinews due to all the cash being funnelled north via the Barnett Formula and similar colonial devices to subvert the nation’s hardihood.

“A party that is now in its second term of office cannot avoid taking responsibility for its own failings.” Hey, what Unionist lickspittle said that? Oh, sorry, First Minister, of course it was you; but that was before you became First Minister and now your party is in its third term of office and Scotland has recorded its worst ever performance in education, which you wanted to be judged on. Tricky one for the spin team.

You could perhaps relocate from education to health as your priority, but with NHS Scotland missing nearly all targets on waiting times, including for cancer treatment and A & E, that might be a case of out of the frying pan and into the fire. The truth of the matter, Mrs S, if you came clean – which, of course, you would never do – is that Scotland has not had a government in any recognizable sense over the past decade. What it has had instead is an independence referendum campaign in permanent session.

It is difficult to spare a thought for schools and hospitals when your attention is focused exclusively on trying to secure and win a second independence referendum. As recently as a few weeks ago Nicola Sturgeon was beating the drum for “Indyref2”; her aides were believed to be working in private on the blueprints for Indyref3 and Indyref4. Now the SNP insists the general election “is not about independence”.

When was anything the SNP ever engaged in not about independence? Until the election was called, Sturgeon’s temper tantrums about a second referendum were becoming manic; now her enthusiasm for that adventure has cooled. Why? Because things are not going well for the SNP, in rather the way that Stalingrad was not an awfully good result for the Wehrmacht.

Several factors have coincided to create a perfect storm that signals the beginning of the end for the SNP. Brexit, regarded by the SNP as calculated to raise Scots’ blood to boiling point and provoke an emotional spasm during which an opportunist referendum would secure independence, has signally failed to deliver. A significant majority of Scots voted Remain, but after that the expected chain reaction petered out.

Not only is there little demand for another referendum, most Scots actively oppose it. The most recent Scottish poll (YouGov for the Times) showed 51 per cent of respondents do not want a referendum in the next five years. Only 37 per cent would support a referendum before the departure of Britain from the EU and only 35 per cent after departure.

So, the SNP would provoke resentment by holding a referendum, but the larger question is: why would they want to? The same poll showed, if a referendum were held, voting intentions would be Yes 45 per cent, No 55 per cent – identical to the result in 2014. What happened to the SNP’s hoped-for Brexit “bounce”?

Then there is the inexorable incumbency factor. The SNP has been in power for ten years. No party can expect to escape a fall in its support after a decade of incumbency: already the SNP is a minority government, reliant on Green support. In theory it does not have a lot at stake in the general election since it holds 56 out of 59 Scottish seats at Westminster and this poll suggests a loss of around nine which, since the post-devolution climate has downgraded the importance of Westminster in Scots’ eyes, would hardly seem catastrophic.

But the SNP is in a unique position which means this election – and any election – matters enormously, more than for any other party. The SNP’s success has depended on momentum. Once that momentum is not only halted but reversed, the jig is up. The headline “SNP losses” is fatal to public perception of a supposedly irresistible surge towards independence.

Nicola Sturgeon is about to be called to account for her neglect of the day job, as evidenced by the decline of Scotland’s public services. If the SNP cannot govern Scotland under devolution, what hope is there of its governing well under independence, with a deficit of 10.1 per cent of GDP – by far the largest in the developed world?

The alarmist questions the SNP raised about Brexit have boomeranged against them by creating concern and its natural consequence – caution – in voters’ minds. Nicola Sturgeon’s is a failed government and it is too late for it to recover. Both voters’ expressed wishes and Theresa May’s imposed timetable dictate that the earliest date a second referendum could be held is after the next Holyrood election when, following 13 years of presiding over Scottish decline, Sturgeon’s minority government can expect to be defeated, removing independence from the political radar.