Nye Bevan once referred to the “language of priorities”, while Tories like Disraeli and Rab Butler cast politics as the “art of the possible”.

They were all correct, which is why talk, much in vogue, of “principle” and “authenticity” is so much hot air. By definition successful politicians are neither of those things; rather, that old Blairite mantra, “whatever works”, better captures contemporary political orthodoxy.

Take the SNP’s approach to a second independence referendum, on which a much clearer strategy finally seems to be emerging. Over the past few days Nicola Sturgeon has rediscovered the “I” word, first in response to Jeremy Corbyn’s victory (which some leftish Yessers of my acquaintance considered crass), and then in terms of articulating the party’s Holyrood manifesto.

This, the First Minister told the Press Association, will “set out what we consider are the circumstances and the timescale on which a second referendum might be appropriate”. But the Scottish Government, she added, can “only propose”; naturally it’s for “the people” to decide, be it “in five years or 10 years or whenever”.

Beyond the obvious point that this finally exposes talk a year ago of the referendum being a “once-in-a-generation” opportunity (Ms Sturgeon herself defined a “generation” as 15 years) for the cynical posturing it always was, it simply isn’t true, as the First Minister claims, that “at every single stage” the process will be “driven by and decided by the people of Scotland, not by politicians”.

That isn’t how politics works, even “new politics”, particularly in relation to referendums. The first independence ballot – which took place a year ago on Friday – was driven entirely by the SNP (with crucial acquiescence from Westminster), and the same will be true of the inevitable second round; sure, voters will have their say, but on “circumstances” and a “timescale” very much determined by politicians.

Ms Sturgeon’s position, however, neatly reflects Scottish public opinion, opposed to the idea of another referendum any time soon, but generally accepting of the fact it might take place in, as the First Minister says, five or ten years’ time. And as she admits in an STV documentary being screened this evening (Scotland, What Next?), “if we are going to have another independence referendum I want to know there is support in Scotland … that means that referendum is going to be successful”.

In other words, “the people” can decide, but only when the SNP deem them likely to make the right decision. Nevertheless the timing of these remarks was significant, for it had got to the point where the SNP base, many of whom are impatient for another ballot, needed a more concrete indication of the leadership’s thinking. As one strategist put it to me: “If the party was asked tomorrow it would choose a referendum next Thursday and we’d lose. She wants to win.”

Now there is a clear, or rather clearer, timescale, and in some quarters the thinking is evidently geared more towards 2020/21 rather than 2025/26. Picture the next UK General Election: George Osborne will have won a mandate as the new Tory leader, while Jeremy Corbyn (assuming he fights the election) will have crashed and burned. Given that Ms Sturgeon’s challenge to Labour – winning the next election – will have failed, a snap referendum might follow on the basis that only independence can prevent another five years of Conservative-imposed austerity.

Either that or the SNP wait until the following autumn, although that comes with the additional hurdle of having to win a third overall majority at Holyrood elections in 2021, and if that doesn’t go to plan then the fall-back option is the same scenario in the wake of the 2025 General Election. After all, it seems unlikely the bogeyman of the currency union veto (Mr Osborne) will go down well north of the Border.

In a new edition of Alex Salmond’s referendum diary, The Dream Shall Never Die, published this week, the former First Minister makes it clear he’s in the 2020/21 camp. “Since the election, and the reaction of the Tories to the SNP landslide,” he writes, “I have thought that ‘indy ref 2’ will arrive on a much sharper timescale”, something no amount of “Tory huffing and puffing” can prevent.

The weakness of this positioning, however, is that it reduces another referendum to little more than a question of tactics. Now it’s self-evidently the case that the SNP are good at tactics, indeed much more so than their Unionist opponents, but not so hot when it comes to practicalities, where they generally fall back on platitudes and assertion. All the evidence suggests certain voters perceive a gap between the rhetoric and reality, and without closing that a second referendum cannot be won.

Some Nationalists realise this. Writing in a Sunday newspaper, for example, the former SNP communications chief Kevin Pringle observed that next time round only “a more balanced approach to discussing Scotland’s strengths and weaknesses” could enable a second independence campaign to “persuade many more people” to vote Yes.

But again, this would amount to little more than a finessing of style rather than substance. When it comes to the big, difficult stuff like monetary policy, there appears to be very little movement. Although the veteran Nationalist Jim Sillars has been agitating for a second referendum predicated upon a separate Scottish currency, some insiders believe the uncertainty surrounding the currency issue has been exaggerated in last September’s defeat.

Nor is there any prospect, certainly judging from the First Minister’s warm words about Her Majesty last week, of a more republican campaign. In fact, the second “Yes” campaign could end up looking very much like the first, just more balanced in tone and much, much shorter. As former Yes chief Blair Jenkins (who also pointed to 2021 as a likely date) observed, this is possible given the “groundwork” laid between 2012-14.

All of this betrays the considerable confidence, at times bordering on hubris, that permeates the independence movement. By contrast, both tonight’s STV documentary and a forthcoming (and very entertaining) book by journalist Joe Pike called “Project Fear” reveal that Better Together was not only considerably more chaotic than was obvious last year, but remains plagued by recriminations and self-doubt.

If there is another referendum in five years’ time it’s impossible to envisage another pan-Unionist front; rather it seems likely there would be separate – and therefore much less effective – campaigns spearheaded by the Tories and rumps of Labour and the Liberal Democrats. Perhaps Mr Corbyn might fashion a left-wing defence of the Union over the next few years, but it’s a tall order.

Over the past few days Ms Sturgeon – emerging as a strategist every bit as shrewd as her predecessor – has put down a constitutional marker, maintained pressure on Westminster and kept her grassroots supporters on side. The SNP leader has effectively fired the starting gun on another five or six-year campaign for independence, and unless her opponents get their acts together soon, in future it could well be viewed as a decisive moment.