Nicola Sturgeon is going. Does that mean the United Kingdom will survive? | Martin Kettle

The political vultures have been circling Nicola Sturgeon for several weeks now. But her resignation as first minister and leader of the SNP still comes as a lightning bolt from a not especially threatening Scottish political sky. It is certain to trigger the biggest convulsion in Scottish politics since the independence referendum of 2014, and its implications will be felt across the electoral and constitutional politics of the whole UK too.

Sturgeon’s resignation statement at Bute House today showed why she will be such a formidable act to follow, and also why it is time for her to go. She had much to say, about Scotland, independence, Covid and political life, which was as eloquently done as ever. But her speech, perhaps like her leadership, went on too long. Even as she spoke, you could sense that the political world was cruelly turning to consider the post-Sturgeon era.

It has been a commonplace among those who track Scottish politics that Sturgeon has been in what one columnist called her late imperial phase for many months. She had begun to lose her touch – and hence her hold – especially when compared with her mother-of-the-nation mastery during Covid. Even within the ranks of her Scottish National party, the most self-disciplined and tongue-holding political force in these islands outside Sinn Féin, criticisms and disagreements were being voiced.

Sturgeon’s departure emerges from a constellation of proximate causes. Her handling of Scotland’s new gender recognition laws – unpopular with the majority of Scots – has been uncharacteristically heavy footed. Her strategy on independence – still the central divide in Scottish politics – has been heading into a constitutional cul-de-sac. Her domestic record as first minister has come under unusually intense and scathing challenge. Her performances in the Holyrood parliament and in her recent press conferences have been second rate, especially from a political leader who was once such an accomplished public performer.

In the end, though, she is surely also going for the reason that she tried to put at the centre of her resignation speech. She has been SNP leader and first minister for eight years now, since succeeding Alex Salmond. She was Salmond’s deputy for nearly eight years before that. There is no ideal number of years for a leader to serve, but Sturgeon’s 16 years – like those of Angela Merkel – are surely too much. As Jacinda Ardern put it, she simply doesn’t have enough left in the tank.

Sturgeon’s departure triggers a leadership contest between contenders who possess only a fraction of her name and brand recognition. The contest will not be like 2014, when Sturgeon was the self-evident SNP leader in waiting. Sturgeon is said to believe that Kate Forbes, the Scottish finance secretary, possesses, as Napoleon once put it, a marshal’s baton in her knapsack.

Forbes is talented but she is also relatively untested. She also comes from a much less liberal progressive background than either Sturgeon or Salmond. Her views on abortion and gender recognition are not Sturgeon’s. It would be ironic if these views equipped Forbes to reach across the political divide in the way that Sturgeon said today she herself could no longer do.

In the short run, Sturgeon’s successor must navigate what will now be a much less predictable SNP special conference next month on independence strategy. Sturgeon made a point of saying in her resignation speech that her departure would free the SNP to choose its path. But this will not be easy or necessarily successful. The SNP stands or falls on independence.

In the medium term, Sturgeon’s departure robs the SNP of its greatest individual electoral asset. It would be outrageous to claim that the SNP has been a one-woman band, any more than it was a one-man band under Salmond. But the SNP always put Sturgeon front and centre of all its electoral campaigns, and without her there will not be the same allure and confidence. For that reason, today was a very good day for Scottish Labour and for Keir Starmer, who will see their general election chances boosted.

In the long run, though, the big question posed by Sturgeon’s resignation is whether this is the watershed moment for the independence cause that unionists quietly crave and nationalists, if they are frank, still fear. Does her departure mean, and reflect the fact, that the nationalist tide has passed its high point? Is the United Kingdom a little more secure tonight with Sturgeon’s going than it was when she was in the ascendancy? Many will think that the answer is yes. But many have been wrong about this very subject before.