Euan McColm: John Swinney's arrogant response to questions over Murrell was straight out of Trump playbook

One moment, the First Minister was his usual enervating presence in the Holyrood debating chamber, the next he was in full, frothing meltdown.

Labour’s Anas Sarwar had, not unreasonably and entirely predictably, chosen to open Thursday’s session of First Minister’s Question Time by raising the matter of former SNP chief executive Peter Murrell’s plea of guilty to embezzling more than £400,000 from the party during his time in charge.

Swinney must have expected Sarwar would lead with the issue. Murrell’s crime spree represents the biggest cow’s arse in the history of devolution, so the Labour leader was always going to come armed with a box of banjos.

But, if the First Minister had prepared for Sarwar’s line of questioning, it didn’t show.

Instead of indicating even the slightest understanding that Murrell’s crimes and the SNP’s role in shutting down questions about them represented a legitimate matter of public interest, he began ranting.

Sarwar had been “peddling” this story for five years and the Scottish people had made up their minds and returned 58 SNP MSPs to Holyrood

“I think,” Swinney added, “that Mr Sarwar should change his script because his script is not working.”

What a car crash.

Swinney’s arrogance rarely surfaces but, when it does, boy is it ugly.

Given the horrifying details of Murrell’s case – the way in which he was able to spend SNP members’ and taxpayers’ money like a QVC addict on blueys, the repeated, thwarted, attempts by party members to get to the truth about money missing accounts, the insistence, even as her husband was stealing huge sums of money, by Nicola Sturgeon that everything was absolutely fine and nobody should ask any questions – this was a moment for humility.

The moral high ground on which Swinney and his fellow senior nationalists had stood for more than two decades has collapsed, unable to bear the weight of a top-of-the-range mobile home, two luxury cars, a drawer full of women’s designer clothing, and enough gaudy tat to decorate an estate of Bel Air show homes.

Swinney’s reply to Sarwar was a “so f***ing what?” from the Trump playbook.

What difference, after all, is there between the First Minister’s sneering dismissal of the significance of the crimes of the man he appointed executive of the SNP and Donald Trump’s famous declaration that he could stand in the middle of Fifth Avenue and shoot somebody without losing a vote?

It seems unlikely to me that, during FMQs prep on Thursday morning, Swinney and his team settled on “The SNP can do whatever the f*** it wants and still beat you” as the appropriate line to take but the First Minister is a man with only two settings – dull and steady, useful in his finance secretary days when this flaw could be presented as an advantage, and furiously angry when his thin skin is pricked.

John Swinney’s triumphalism is made doubly distasteful by the fact the full truth about the SNP’s role in concealing Murrell’s crimes was withheld from voters until after polling day. Last week’s court hearing had been scheduled to take place on February 20.

Had Murrell pleaded guilty at that time, the result would have been very different.

Hah! Says the tribally loyal Nat, insisting this assertion is unprovable, we’d have won no matter what.

But no serious SNP politician, if any remain, believes for a minute that the drab and uninspired Swinney would have secured his party’s fifth successive win if voters had known not only about Murrell’s crimes but had witnessed his reaction to questions about them.

Swinney retains the support of his cabinet. The feeling among ministers is that he is being forced to deal with a problem not of his making.

The real anger among the upper echelons of the Scottish government is directed towards Nicola Sturgeon. To say she is now persona non grata among former allies is an understatement.

The former First Minister is despised by people who once followed her every instruction.

But, while Swinney’s team remains onside, support is qualified.

For now, colleagues believe the First Minister still has room to manoeuvre through this crisis but there is unease about what might yet emerge about the culture within the SNP that allowed Peter Murrell to spend, spend, spend like Viv Nicholson.

One needn’t be an expert in human behaviour to read John Swinney’s furious reaction to questions from Anas Sarwar – and, later, Scottish Tory leader Russell Findlay – as fear, rather than indignation.

For many years, the SNP was controlled by a powerful quartet: Alex Salmond, Nicola Sturgeon, John Swinney, and Peter Murrell.

Swinney can play the outraged victim all he likes but this is a scandal about much more than the theft of some money from SNP members by a lone wrong ’un. Rather, the Murrell case throws the focus – for the umpteenth time – on the institutional dishonesty of a party characterised by cover-up and lies.

The First Minister helped create the SNP culture that allowed his friend of more than 30 years to fill his boots with money received from both supporters and the Treasury.

Swinney should think himself lucky he is First Minister. His victory does not belong to him but to the Crown Office, which agreed to delay Peter Murrell’s case.

Sometimes a political scandal is so great that it demands a scorched-earth approach.

If John Swinney can’t disentangle himself from the Murrell scandal, he risks becoming just another liability for his party.

Ambitious pretenders to the first ministerial throne should begin drafting campaign speeches.