It was a cleverly crafted speech from Nicola Sturgeon, by far the UK’s longest-serving party leader; she used bright splashes of colour, judicious notes of caution, and delivered it with conviction. Yet what was equally noticeable was what she did not say. For all the optimism and confidence-building Sturgeon offered around the case for independence, there was much less clarity and certainty about how it might be delivered. Her speech left that question, the biggest question of all, hanging in the air. Four months ago, the first minister had shocked her opponents, and many supporters, by proposing that the next general election could be fought, in her words, as a “de facto” referendum on the single issue of independence. That, she told the Scottish parliament in June, would be the Scottish government’s central strategy if the UK supreme court rules in the coming months that she cannot stage a referendum without Westminster’s approval. It was audacious. She was suddenly embracing a radical proposal first proposed by some of her internal critics and one she had previously dismissed. She also seemed to have abandoned her promises that independence could only be won by aiming for the “gold standard” of legality and legitimacy. It was risky because it relied on the Scottish National party, and perhaps other pro-independence parties, winning more than 50% of the popular vote. The SNP has only come close to that figure once at a general election, in 2015, when its manifesto stated unequivocally that independence “is not what this election is about”. Last week a series of Scottish opinion polls put Labour above 30%, without any gain for the SNP. It was Labour that benefited from the chaos and economic turmoil generated by the Conservatives in London. Senior MPs and advisers had already been advising Sturgeon to walk away from her de facto referendum pledge; those polls made their warnings real. So in her conference speech on Monday, Sturgeon spoke simply of putting “our case for independence to the people in an election”. No mention now of a “de facto” single-issue campaign. Perhaps it is all just a matter of timing. By coincidence, at 10am on Tuesday the supreme court will start hearing evidence on whether Scotland can stage a legal referendum without Westminster’s consent. For the next two days the Scottish and UK governments will fight it out in front of five senior judges; in their hands sits the immediate fate of the Scottish independence movement. Sturgeon has grasped the delicacy of the moment. There was none of her bombast from June. Instead she warned the 1,000 or more rapturous delegates in the hall the SNP could lose. In that event, “obviously, we will respect that judgment”, she said. “We believe in the rule of law. And as a party – and a movement – we will, of course, reflect.” And equally significantly, Sturgeon openly changed her tone with her opponents. On Sunday, she had triggered a furious backlash when she told Laura Kuenssberg she “detested the Tories and all they stood for”; Tory critics warned that incendiary tone could provoke violence. It also contradicted her insistence recently that respect and tolerance were needed in politics. Perhaps with last week’s polls in mind, and with a hint of an apology, Sturgeon offered an olive branch to unionist voters. She said she respected their opposition to independence: “Please remember, whatever happens in future, Scotland belongs to you as much as it does to us. Scotland belongs to all of us.” Given how volatile British politics is at present, it would be risky for unionists to assume their slender polling lead will last. It is noticeable, however, that Sturgeon dampened the yes movement’s expectations. “It is tempting, sometimes, to assume an inevitability about independence. That the arc of history is moving firmly in its direction. [But] we would be wrong, utterly wrong, to take it for granted.” She told activists they still had to “win the argument”.