There usually comes a point in the cycle of power when strength becomes weakness, when the qualities that first made a leadership group a success become a handicap. There are indications that this may be happening to Nicola Sturgeon, whose response has been unimpressive in the wake of last week’s local election results. The Scottish Tories surged and the SNP won but lost momentum, which was not in the Nationalist script.

Sturgeon has gone into overdrive in recent weeks, nodding away at ever greater speed in TV clips and losing her cool, saying “Torees, Torees, Torees, hurd Toree Brexit, Torees, Torees, Torees” (as though that wins an argument) with such repetitive force that I feared for her. I wondered last week if her brain had got stuck on the word. “Toree” (Tory) has been the trigger word in Scottish politics for more than a quarter of a century, a fallback that is code for English, foreign, unScottish or alien. That is not working against the formidable young Scottish Tory leader Ruth Davidson. Sturgeon looks furious that she, Nicola, is old news. What happens when leaders start to lose it?

Margaret Thatcher is the most obvious warning from recent history. She was not an asset in 1979, despite having earned the “iron lady” moniker from the Soviets. By 1983 she was the warrior queen of the Falklands War. In the following seven years, despite numerous achievements along the way, she steadily became less tolerant of dissent. Thatcher fell for her own myth, and was vulnerable to internal challenge when the public grew tired and the economy wobbled.

Tony Blair’s flexibility and eagerness to please were an asset at first. And then he ran into the Bush administration and Iraq.

David Cameron’s great strength in office was his reasonableness, which when coupled with a gift for “essay crisis” redemption‎ enabled him to get out of scrapes. Until he came to rely on it and it suddenly didn’t work at a critical moment, in the EU referendum.

The SNP is different. By that I mean that the UK parties are used to ups and downs, these generational cycles in which lessons are learned, unlearned and relearned via the rise and fall of leaders. It is healthy. And while the UK Tories now are dominant, the economy will turn at some point (it always does and it is overdue a downturn almost ten years since the last crisis). Then there will be space for a moderate centrist or centre-left alternative to challenge for power. Whether or not it is the Labour party or a new force remains to be seen. Up and down politics goes over the centuries, with the Conservatives the most adaptable party of the lot.

The SNP exists to go forward to the goal of ending the UK. Until the 1960s this enterprise was a fringe joke. Evelyn Waugh in the Sword of Honour trilogy is funny on fictional Nationalist pro-Nazi crackpots based on some real-life Nats of the 1940s who willed a German triumph. Then, after the end of Empire (a partly Scottish creation from which the country prospered) North Sea oil was discovered. The SNP had a grievance to go with its cause. It was “Scotland’s oil,” they said. Demands grew for an Edinburgh Assembly.

Since the 1960s the trajectory for the SNP, as a moderate centre-left party, has been mostly upwards. Along the way there were setbacks – such as the loss of MPs after the 1970s peak, and a long plateau. But this was deceptive. Labour was ready to give the SNP the tools and materials to build the next stage of the push to independence. Labour’s conversion to devolution and the growing unpopularity of the Tories north of the border meant that the first time Labour got its act together across the UK the resulting government introduced devolution in 1997.

The Nationalists under Alex Salmond used this opportunity brilliantly, transforming the SNP into a party of government‎ that has smashed Scottish Labour, building a coalition that spans the left and the right and urban and rural Scotland. From that base they progressed to a referendum in 2014 in which they came close to breaking up the UK. They then won 56 of Scotland’s 59 Westminster seats.

It was going tremendously well and the excitement was intoxicating for Nationalists. Hubris abounded at the turn of the year. When Brexit happened it seemed clear to the faithful what followed as night follows day. A furious Scotland would be angry at being taken out of the EU, demand a second independence referendum and vote to leave the UK and rejoin the EU.

Awkwardly – cussed people those voters – that is not what has happened. Many of the 62% of Scots who voted Remain are pro-UK. They resent having their Remain vote filed in the Nationalist column, a point Ruth Davidson (a Remain voter) makes to good effect. A third of SNP voters were for leaving the EU, too, meaning that the SNP has had to back away from its EU-fanaticism a little, while still seeking a referendum on the basis of Brexit. It doesn’t stack up. The basic logic is flawed and non-Nationalists can see it.

Sturgeon’s audacious demand earlier this year for a referendum mid-Brexit was hailed at the time in much of the London media as a stroke of strategic genius. On the contrary, it looks during this general election like a serious miscalculation when the majority of Scots don’t want another referendum on leaving the UK, or certainly not soon.

Scottish people who are not activists or crazed party fanatics are, like voters across the UK, generally sensible. They know Brexit is complicated enough and an independence referendum in the middle of it is a daft idea. The SNP has also been in power for a decade and has done a poor job on Scottish education, health and the economy. Shouldn’t Sturgeon and her lot get on with that rather than being fixated on securing Indyref2? Yep.

Nicola Sturgeon has also started to really annoy non-Nationalists. You have to visit Scotland to get the full sense of the backlash, after years in which people kept their voices down for fear of social retribution. The initial Sturgeon promise of reaching out has been replaced by increasingly intemperate strutting about and a refusal to even acknowledge, with a dash of humility, that not everything is wonderful in the SNP garden. Sturgeon said any talk of a “backlash” against her is “ludicrous”. She’s gradually going the full Thatcher.

It is in that context that last week’s local elections in Scotland should be viewed.‎ The SNP came first, of course it did. The tally of 431 (-7) seats was in and of itself impressive. The Tories surged on 276 (+164), Labour finished down at 262 (-133) and the Lib Dems settled on 67 (-3).

Incidentally, there was an undignified little row the seat numbers, with the chief executive of the SNP (Mrs Sturgeon’s husband) accusing the BBC of undestating the Nat tally. This brought down the full might of the cybernat online nuts on the Beeb. Lost in the row was the reality that the Beeb had simply adjusted for boundary changes in an effort to be fair.

Meanwhile, Nicola was out on TV saying with a fixed smile that all was grand and 100% as intended. It all smacked of the Sturgeon family business suffering a glitch, with the boss out front smiling saying those misfiring noises from the engine-room were nothing to be concerned about.

What must be remembered about the results is that the SNP was supposed to knock it out the park last week. It took Glasgow but fell short of overall control and suffered setbacks in other areas. A country demanding a second independence referendum (Scotland isn’t and that’s the problem for the SNP) would surely give the SNP a big increase in council seats. The last time these council seats were contested was 2012. In the intervening five years the SNP has become a mass membership party of considerable prowess and won, remember, 56 seats at Westminster. This was supposed to be the local authority map catching up with electoral reality and massive advances. Instead? Party meet plateau, and maybe with worse to come.

And on June 8th? It’ll be tough for the Tories, even though something has stirred with voters who have had enough. The SNP is defending 56 seats and has large majorities. It has an extraordinary machine at its disposal too, and an activist base it will throw at vulnerable seats. The fight has already got nasty and will probably get worse.

This is because so much is at stake. The Sturgeon hegemony is built on the idea that the journey is almost over. The SNP is almost at its destination, with just a few more touches on the accelerator needed. Now, the SNP juggernaught is stalling and potentially Ruth Davidson is about to start pushing it back down the hill. If the Unionist parties force the Nationalist vote share down and the SNP falls anywhere below 50 seats they will very obviously and publicly have begun to go backwards.

This all runs counter to the Nationalist narrative of destiny and imminent success on the constitution. The events of the last three or so years were supposed to be the prelude to independence becoming inevitable. Right now it just isn’t working out the way they intended, which is hilarious.