A pox on all their houses, but on some more than others. This seems to be the mood of the average Scottish voter today.

A fascinating new poll in this morning’s Times doesn’t make comfortable reading for the party leaders, at least as far as their personal popularity goes. Nicola Sturgeon’s rating has slipped below zero - the 45 per cent of voters who judge her to be doing well is trumped by the 47 per cent who say she is doing badly, leading to a score of -2.

Ruth Davidson remains in the black, on an overall positive rating of 11, but that number is down by four points. And poor Richard Leonard. The Corbynite Scottish Labour leader, who has now had a six-month run in the job, has made little impact – and what impact he has had has taken the party in the wrong direction. A whopping 54 per cent gave a “don’t know” response when asked how Leonard is doing – this includes 57 per cent of those who voted Labour in 2017. Only 13 per cent believed he was doing well, compared to 33 per cent who said he was doing badly. An overall score of -20. Not great.

But then, these numbers look positively North Korean when compared to Scots’ views of Westminster’s leaders. Theresa May is on -44, Jeremy Corbyn on -30.

It is Sturgeon – whose party’s spring conference starts in Aberdeen today - who will take most comfort from the figures. Voting intentions for Holyrood show support for the SNP at 41 per cent, an increase of three points, and for Westminster the party is on 40 per cent, a rise of four points. This is remarkable, given the Nats have been in power in Scotland for the past 11 years.

It’s estimated these results would give them 43 seats in London (with Labour losing all but one of its current seven), and 54 in Edinburgh, which would be a drop of nine but still make them the largest party by some way. Ruth Davidson’s Tories would be second at Holyrood, on 33 seats. There would however be a unionist majority – the Tories, Labour and Lib Dems would have 66 of the devolved parliament’s 129 seats, compared to 63 for the SNP and the independence-supporting Greens.

What does it all amount to? The psephologist John Curtice says Sturgeon, despite the drop in her personal ratings and the threat of losing the pro-independence majority, must hardly believe her luck, given what appears to be Labour’s continuing, long-term collapse north of the border. “If the First Minister momentarily lifts her gaze across to the Labour benches she will have difficulty counting her lucky stars, so numerous they seem,” he writes. As well as Leonard’s failure to cut through, “until now, Labour could comfort itself with the thought that it could rely on the rock-star like popularity of Jeremy Corbyn… those days seem to be over.”

Leonard’s brief tenure has been characterised by a sharp shift to the left, in an effort to win back traditional Labour voters who have defected to the Nats in the belief that independence would be more likely to deliver socialism. But he has done so at the expense of wooing Middle Scotland, which seems barely to have noticed his presence. It doesn’t help that in Sturgeon and Davidson he is up against arguably the UK’s two most impressive politicians. If the aim was at the very least to win back the role of official opposition from the Tories, he’s failing there too.

The polling was carried out from 1-5 June, which was shortly after the publication of the SNP’s Growth Commission report. It’s unlikely many respondents had read the 350-page document, but its authors will nevertheless breathe a sigh of relief that their findings do not seem to have had a negative impact. Or at least not yet.

The Yes movement has been locked in something of an existential trauma since the commission unveiled its dramatic conclusions. The report’s acceptance that an independent Scotland would start out with a multi-billion-pound deficit, that there would be no oil bounty, and that the first 10 years at least would be a tough ride, was a marked shift from the starry-eyed optimism of 2014. This has both infuriated and devastated the radical left, which dominates the campaign for a second referendum.

The commission’s report, endorsed by Nicola Sturgeon, has allowed the mainstream SNP to seize back control of the independence narrative. The relative frankness about the precarious state of Scotland’s economy has also sparked a broader - and, potentially, cross-party - discussion about how the nation’s lamentable growth record can be improved under the existing devolution settlement.

This is the context in which Sturgeon will deliver her conference speech on Saturday. Despite the unpopularity of Brexit in Scotland, despite intense pressure from within her party and the wider movement to go for a second referendum, the First Minister must know it would be a gamble to seek a new vote when support for independence remains stuck fast around 2014’s 45 per cent level. If it hasn’t been explicitly stated, there’s a sense the SNP leadership could perhaps be shifting towards a strategy of using its governance powers, rather than fiery rhetoric, to shift the dial on independence. The calculation is: make a measurable difference on economics and public services under devolution and Scots will be more willing to make the final leap.

Sturgeon’s speech will have to address disquiet among some members about the implications of the Growth Commission’s findings and explain how this new realism can succeed where the boosterism of 2014 failed.

But she will be bullish. With a bit of perspective – and setting aside the challenge of securing separation (which of course the nationalists aren’t willing to do) – the SNP’s defiance of electoral gravity is utterly remarkable.

Sturgeon is undoubtedly a lucky general. The Brexit mess at Westminster will remain a millstone for her opponents. And the First Minister will take heart from the longer-term omens – a second poll published today found Scots are more confident than before about the financial consequences of independence. Researchers at the National Centre for Social Research, which published the data, noted this was “further evidence that the climate of opinion is now more favourable to the idea of leaving the UK as compared with the position before the independence referendum.”

Whatever the reasons, her personal hegemony and her party’s grip on power look set to run for some time yet. For that, at least, she’ll be cheered to the echo in Aberdeen.