The late William McIlvanney once observed in this newspaper that national identity was “like having an old insurance policy”.

“You know you’ve got one somewhere but often you are not entirely sure where it is,” he wrote in 1999. “And, if you’re honest, you would have to admit you’re pretty vague about what the small print means.”

At some point this week, we’re led to believe, the First Minister will be updating an anxious nation on her plans for a second independence referendum, and reports suggest she intends to deploy a similar simile in her efforts to keep the “dream” alive.

It first cropped up a week or so ago when the new SNP leader at Westminster, Ian Blackford, said any referendum, “if it were to happen” (an interesting caveat), would be an “insurance policy on the future of Scotland being impacted by a hard Tory Brexit that damages our interests”.

Yesterday a source also told a Sunday newspaper that Nicola Sturgeon wants to achieve a soft Brexit for the whole UK or, failing that, Scotland. Voters would then being free to “judge” independence after negotiations have concluded. “Presenting the issue as a choice we can exercise in future works,” the insider added, “as does describing independence as an insurance policy.”

So a second referendum, once described as “highly likely” and a moral imperative by the First Minister, has now been relegated to a piece of paperwork, something its holder hopes will never be used. Crucially, an insurance policy doesn’t sit “on the table” (to deploy another well-worn image), but at the back of a drawer. As one former SNP adviser put it to me, it has moved from being “on the table” to “under the table”.

Good luck selling that to a majority of the electorate. As usual, this (likely) response to the loss of 21 seats and 13 per cent of its vote at the recent General Election is an elegant fudge, a piece of triangulation that’s come to characterise the modern SNP. But the trouble is it’ll end up pleasing no-one: the broader Yes movement will struggle to march in favour of an insurance policy, while Unionists, chiefly the Scottish Tories, will argue that a blinkered First Minister is ignoring the will of the people by keeping another referendum in play.

It might at least reconcile different views within the party. Since June 8 a remarkable number of senior SNP figures have volunteered their views to the mainstream media as to future strategy. Brexit minister Michael Russell says the Scottish Government’s view “hasn’t changed”, while Richard Lochhead, Alex Neil, Kenny MacAskill and Tommy Shephard have, in various ways, urged Ms Sturgeon to “park” another plebiscite.

Another problem for Nationalists is that downgrading the referendum policy risks robbing the party and wider independence movement of its lifeblood. For seven years after the SNP entered devolved government in 2007 it was sustained by the prospect of a ballot on independence. Even voters who didn’t agree liked this sense of “vision”; it gave the rebranded Scottish Government form and purpose.

Since the autumn of 2015, however, the independence “force” hasn’t been as strong. Following the European referendum just over a year ago, the First Minister tried to resuscitate it by placing a second plebiscite “on the table”, but it fell demonstrably flat: not only did Scots fail to rise up in indignation at “perpetual” Tory rule and being “dragged out” of the EU, but Theresa May called her bluff with a (sort of) veto and a snap General Election. The result? The Scottish Tory vote doubled amid a clear backlash against the prospect of another “ScotRef”.

In policy terms, that would count as a failure, but as other commentators have been asking recently, without independence, what precisely is the point of the SNP? Not only has the (always tenuous) “utilitarian” narrative has been heavily undermined by the surprise emergence of Jeremy Corbyn as a possible UK prime minister, but the “big tent” erected by Alex Salmond is sagging under the weight of its own considerable contradictions.

Last week a number of issues – tail docking, cutting Air Passenger Duty and the falling number of college places – highlighted this as never before. Watching from Holyrood’s press gallery, it looked like the SNP’s imperial phase was well and truly over, something inseparable from the strategic decisions of the First Minister herself. It was Ms Sturgeon who married independence so closely with Brexit a year ago, something that looked unwise at the time and increasingly so since. As Euan McColm observed yesterday, the SNP leader became so convinced a “catastrophic” Brexit would push No voters into the Yes camp she lost sight of the fact that it also undermined the idea that “Scoxit” would somehow be plain sailing.

Appalled by the economic and constitutional fall-out from Brexit? Here’s some more! And if a second independence referendum is an “insurance policy”, then what McIlvanney called the “small print” is important. Not only does it remain vague on the question of re-joining the EU, but the premium will be £15 billion a year in lost Barnett consequentials. It’d take a pretty good salesman to make much commission on that.

Sturgeon appeared to trail this week’s big speech during a visit to the Royal Highland Show a few days ago. Achieving a “soft” Brexit, she said, was her “absolute priority” (I thought that was supposed to be education?), while a second referendum would be held “when the time is right”, which marked the final death knell for the autumn 2018-spring 2019 timetable set out by the SNP leader just a few months ago.

All this leaves the rationale for independence in a rather strange place. Not long ago Ms Sturgeon informed us this transcended everything else, a very existentialist view, while now it appears to be predicated upon achieving a more acceptable form of Brexit for the whole UK. If a second referendum is to be a compelling “insurance policy” against a hard Brexit, then it’ll take much more than a rhetorical reboot by the First Minister.