This week saw another spoke jammed in the chariot wheels of Nicola Sturgeon, the Scottish First Minister apparently driving all before her on a tsunami of Covid propaganda and chauvinist confidence. The revelation that the Scottish Nationalist MP, Margaret Ferrier, had twice travelled by train between Scotland and London despite having symptomatic Covid has created huge embarrassment for the SNP.

Ferrier had the SNP whip suspended immediately and Nicola Sturgeon called on her to resign her seat. The First Minister’s embarrassment was compounded by the fact that Margaret Ferrier was vocal in demanding the resignation of Dominic Cummings for his trip to Durham, which she said had “undermined the sacrifices that we have all been making” and described his position as “untenable”. Yet Cummings at least travelled by private car, whereas Margaret Ferrier’s behaviour was that of a Covid super-spreader.

The reason Nicola Sturgeon is so alarmed by l’affaire Ferrier is that it subverts one of the SNP’s principal weapons: the pretence of moral superiority. Nationalist rhetoric has always been tinged with a pronounced note of sanctimony; it is a cultural hangover from Scotland’s Calvinist past. That aggravates the embarrassment of being exposed for hypocrisy. Nor is the scandal provoked by the Ferrier revelations the only factor derailing the Sturgeon hubris.

Storm Alex has a more than meteorological significance in Scotland. The backlash from the Alex Salmond prosecution and acquittal, now the subject of a parliamentary inquiry at Holyrood, has raised political flood tides that are now lapping around the feet of Nicola Sturgeon and her husband, Peter Murrell, chief executive of the SNP, with claims that Murrell tried to incite police investigation of Alex Salmond. Meanwhile, the inquiry has ground to a halt, with its convener Linda Fabiani saying that she and her colleagues were “completely frustrated with the lack of evidence and, quite frankly, obstruction it is experiencing”.

The SNP has just hired a senior Scottish law firm to help it cope with the inquiry. This week a Conservative MSP was ejected from the chamber for refusing to retract a claim that the First Minister had “lied to parliament” and Ruth Davidson asked Sturgeon what had made her “break her word”. Sturgeon’s enemies, sensing blood, are circling; but her worst enemies are within her own party – Alex Salmond’s aggrieved supporters, determined to avenge an alleged conspiracy against him.

So, despite opinion polls heralding an SNP landslide at next year’s elections and a narrow majority in favour of independence, the party’s position is less secure than it seems. The SNP imagines that, post-Covid, Scots will opt for separatism. But why would they? Pre-Covid, Scotland had a deficit of £12.6bn, or 7 per cent of GDP, compared with 1.1 per cent for the UK, and oil revenues were a paltry £1.2bn. After the Covid crisis, the precise extent of economic carnage can only be guessed at, but it will make the previous unenviable situation look favourable.

Now outside the EU, and with years of negotiation required for readmission, including adoption of the euro currency, Scots would find they had abandoned membership of a Union of 66 million people, in which state spending in Scotland is £1,661 more per person than the UK average, to submerge themselves in a harshly integrationist union of 446 million people – in the name of “independence”. Canny Scots will think twice about that in the sobering privacy of the polling booth.

Sturgeon’s woes are piling up. Some previous SNP voters are now threatening to withdraw their support in protest against the proposed elimination of free speech by the party’s totalitarian Hate Bill. Above all, there is the fact that by the next election the SNP will have been in power for 14 years, with an objectively verifiable, statistical and severe decline in education, health and other public services as the outcome of its stewardship.

Nicola Sturgeon’s government looks superficially unassailable at the moment; so did Boris Johnson’s administration as recently as last December.