WHAT’S that strange susurration? That weird sound? Is it chickens coming home to roost? Is it nationalist knees knocking?

It’s probably both. The SNP committed a cardinal political sin, now the price is being called in: the party took all those former Labour voters who leant nationalists their support for granted; the SNP thought them corralled and banked; it sneered and mocked at the notion these voters could ever return to Labour. Now Labour is back, and the SNP looks set to lose Glasgow, as the city returns red.

Polls show Labour likely to gain 23 seats in Scotland at the next UK election, as the SNP loses 21. On the current trajectory, Labour takes 24 seats, SNP 27, Conservatives four (down two, with Douglas Ross’s seat kiboshed), and LibDems steady on four. The good news for everyone is that the two defectors from the SNP to Alba – Neale Hanvey and Kenny MacAskill – get kicked out on their ear. Just deserts, for those too craven to stand for reelection once they’d turned tail.

Some big SNP names look set for the bin, including Mhairi Black. There’s a certain irony here. Ms Black has banged on about how it’s meaningless whether Tories or Labour get elected at Westminster. That’s just nonsense. To equate even Sir Keir Starmer’s insipid excuse for a left-wing party with post-Brexit Conservatives is laughable. Every voter in Scotland, save the most partisan nationalist, sees through this. Now Ms Black could discover the difference a Labour government makes as she seeks a life after Westminster.

Read more: SNP dices with death if it props up Tories at Westminster

Losing a key citadel like Glasgow will be psychologically destructive for the SNP. It was the bastion nationalists always wanted to dominate – had to dominate, if they were to rule Scotland. If Glasgow falls, then SNP morale goes cliff-diving. Humza Yousaf – already struggling to exert authority – will see his power further diminish. It’s a fair assumption that if the polls play out as predicted, then knives will be sharpening for him. Factions have already formed – Ash Regan’s Alba-lite, Kate Forbes’ social conservatives.

The SNP has nobody to blame but itself. It’s a party of shameless, idiotic complacency. It plotted for years to take Glasgow and then did nothing with its custodianship. Glaswegians were badly served by the SNP. Like the party at Holyrood, the SNP in Glasgow talks big but lives small. Patience has run out.

The most self-lacerating form of complacency, though, stems from the SNP’s attitude towards Labour. En mass, SNP leaders and supporters have been unable, incapable, of recognising the threat Labour posed. As each poll showed an upswing for Anas Sarwar and Sir Keir, and a downswing for nationalists, the SNP scoffed. "Why would anyone who voted SNP switch to the Red Tories?" they sneered. "Why would anyone who voted for independence back a party whose leader embraces Brexit?" Perhaps, the SNP should get out its violin and play Nearer my God, to Thee. It has the mindset of the band on the Titanic: clinging on to blind delusion in the face of looming catastrophe. Nationalists could never accept that voters might swing back to Labour, believing Brexit their get-out-of-jail-free card.

Seemingly, many pro-Europeans have reluctantly come to terms with the folly of Brexit. They don’t back it, but it’s done and years have passed. For all his numerous faults, many see Sir Keir as engaged in some rather ghastly but necessary realpolitik: to get over the line in England, he must pose as someone embracing Brexit. He needs that Red Wall back. He’s also, importantly, promising better relations with Europe. When it comes to many pro-EU voters and Sir Keir, it’s a case of discomfort trumping agony. There’s a sense – a hope – that he will be more radical and Left in power, that he’ll ditch the Tory-lite approach. Clearly, there’s every likelihood that hope is misplaced. Nonetheless, this appears to be the mood among a swathe of the electorate.

The SNP’s "Red Tory" rhetoric has, evidently, backfired. It made nationalists seem prepared to allow the Conservatives back in: that they were high on their own supply, and too full of the lies they were dishing to the electorate. The Red Tory guff doesn’t wash. Any SNP figure still peddling that is simply cutting their party’s throat.

Significantly, it also seems that the culture war nonsense that’s obsessed the press – specifically the right-wing press – has done precisely zip. Votes are transferring from the "progressive" SNP to the "progressive" Labour Party, so nobody is bailing over trans wars and freedom of speech phantoms.

Read more: Why Humza Yousaf is right to snub Yes marches

Voters are bailing because the SNP just hasn’t governed Scotland well enough. The SNP hasn’t been the Tories: it has not torn the country to pieces. But it has spent so much time chasing independence that it has et Scotland stagnate. In a land of food banks, any government that hasn’t broken its back for the people will suffer, and deservedly so.

Perhaps, the grim solace for the SNP is that support for independence remains pretty unchanged. Roughly half the nation – give or take – are still Yes voters. Nationalists thought independence was a shield that would defend them forever; that once a voter backed independence, they were the SNP's possessions. Again, the SNP took voters for granted, thought the electorate stupid. Voters can perfectly well separate out their views on the constitution, from their view of who best serves their needs in government.

Read more: Scotland can move forward with indy decoupled from the politicians

Now, clearly, the SNP remains Scotland’s dominant party on current polling. Support hasn’t evaporated. But we’re still some way out from the next Westminster election, and opinion is only going one way.

What bodes worse for the SNP is that if its nose is badly bloodied at the next UK election, which will happen sometime before January 2025, its fate will be sealed at the Holyrood election in May 2026. A wound will become a haemorrhage, and that could be the end of SNP power in Scotland.

Can the party reverse its fortunes? Well, yes, of course. As everyone with a brain in their head has been saying for years now, the answer is simple: govern well. But the SNP is deaf to that advice, because, well, the SNP thinks it knows better. First hubris, then nemesis. It’s always the way.