Listeners switching on the Today programme on Friday 24 March must have imagined they had accidentally tuned in to a spoof interview of the Bremner, Bird and Fortune vintage, featuring an embattled government minister crumbling under interrogation.

Nick Robinson was interviewing Aileen Campbell, Scottish Health Minister, who had come on air to crow about the SNP government’s generosity in announcing it would fund three free cycles of IVF treatment for Scottish couples desirous of having a family. Robinson ungenerously chose to rain on her parade: instead of writhing in mute admiration of this taxpayer-funded largesse he pointed out that this commitment would cost “many millions” at a time when a Glasgow maternity hospital had to turn away expectant mothers, Scotland was missing A&E targets and the BMA had described the Scottish NHS as “near breaking point”.

The minister was clearly dumbfounded by this impertinent attempt to hold her to account – something that would not happen in a Scottish media context where hacks know their place in a burgeoning one-party state – as emerged in the climactic moments of this car-crash interview. Robinson persisted in demanding whether free IVF was the right priority.

Robinson: “Why spend money on that when your own A&E target you are missing and have done for a long time?” Campbell: “I understood I was here to talk about the very positive announcement of allowing couples who are desiring to have a family to get access to three cycles.”

Yeah, right on, Ms Campbell, that needed saying. Sassenach journalists need to learn that SNP spokesfolk do not go on the air to be interrogated about unhelpful topics such as crises in maternity hospitals and A&E, or meltdown in Scottish education, now trailing Vietnam in some subjects. If crude metropolitan broadcasters want access to SNP ministers they had better learn the rules of the game. An interview should not be abused as an opportunity to hold a minister to account; it is essentially the broadcast version of a triumphalist press release advertising the latest expenditure by the Scottish state on progressive objectives.

If London-based hacks, notoriously the tools of the English Tory-fascist state, are allowed to get above themselves, before you know it they will be raising unhelpful topics such as the Barnett Formula and certain inequalities in per capita expenditure north and south of the Border. Can they not grasp the simple equation that Scotland, but for English rule, is the richest country in the world with massive oil revenues of £60m, more than adequate to support independence, but with massive needs that require £1,720 additional expenditure per skull over England and 16% over the UK average?

The Scottish Health Minister’s car-crash interview was just one straw in the wind, rapidly assuming the proportions of a hurricane-borne haystack, signalling the end of the SNP’s decade-long free ride from UK media and Scottish electors alike. It has long been a maxim of the Scottish (and sometimes UK) chattering classes that Nicola Sturgeon is a political genius, as was Alex Salmond before her. Few seem to have asked themselves why, in that case, the Scottish independence referendum of 2014 was lost by a margin of 10 per cent.

The reality that Sturgeon is a shrill, unimaginative politician imprisoned by her obsessive constitutional preoccupation in a tunnel vision that precludes her addressing the everyday issues of government has too long been ignored. The SNP has lacked political opposition or even interrogation by the media. Why govern when you can grandstand? The SNP came to power on a programme of deception; its power is now imminently dissolving in a welter of self-delusion.

The referendum loss of 2014 signalled the beginning of the end. The SNP refused to acknowledge the peril in which it stood and convinced itself Brexit would provoke a terminal Scottish alienation from the UK. Within days of Article 50 being triggered, the latest opinion polls on independence stand as follows: YouGov Yes 43%, No 57%; Panelbase Yes 44%, No 51%. So much for the Brexit boost to independence.

In a fit of post-referendum realism, Nicola Sturgeon committed herself to a self-denying ordinance whereby she would refrain from calling for a second independence referendum until support for separatism had stood at 60% for a minimum of twelve months. Yet, instead, this month she announced her desire to hold a second referendum in 2018-19, just when the Brexit negotiations would be at their most problematic. The calculation that an electorate that rejected a leap in the dark in the more stable conditions of 2014 would be game for a much greater gamble at the height of Brexit uncertainty is, to say the least, ill-founded.

That piece of gesture politics has badly damaged Sturgeon’s dwindling credibility. She compromised that crucial credibility in order to indulge in the playground politics of wrong-footing Theresa May for 10 days. In Scotland, more and more people are beginning to ask what the hell has happened to their key public services, notably health and education, on the SNP’s watch. That re-focus on bread-and-butter issues is potentially lethal to the SNP. How can they blame England for Scottish woes wholly devolved into their responsibility?

The slide is, so far, undramatic but evident. The SNP is now a minority government sustained by fruitcake Greens, at a time when, globally, the green tide is receding on a wave of scepticism. In the interests of the UK Theresa May has a duty to postpone a destabilizing Scottish independence referendum until Brexit has bedded in. That probably means until after the next Scottish elections when policy chickens coming home to roost are likely to put the SNP out of power, after which the tedious “indyref” obsession will be off the political radar.

Realizing the danger of the political situation, veteran nationalist Jim Sillars has urged Sturgeon to “do a Hammond” and scrap the massively unpopular Named Person scheme, giving state monitors greater rights than parents over Scottish children, already struck down by the Supreme Court. The SNP needs to divest itself of unnecessary political controversies if it is to survive. The clever money is now on its failure to hold onto government.

Behind the bluster and grandstanding Nicola Sturgeon is a mediocre politician who holds few cards, shouting to keep up her supporters’ courage in the face of long delayed but inexorable nemesis. Eventually, her political tombstone may bear the epitaph: “She made the English media take notice”.