Minority sects are often more interesting, and more colourful, than their more popular rivals. That must explain why the Scottish Tories continue to be the subject of so much fascination. Barely a month passes without someone, somewhere, asking if this — at long last — is the moment for a Scottish Tory revival. Spoiler alert: it never is.

Logic says that at this year’s Scottish parliament elections, things should be different. It is generally agreed that Ruth Davidson, the party leader in Scotland, had a ‘good independence referendum’; generally agreed, too, that after Nicola Sturgeon, she might be the most impressive politician in Scotland. This might be reckoned a low bar to clear; it remains the case that Davidson is the first Tory in a generation who can even think of clearing it. Everyone loves Ruth; very few people will vote for her. This has consequences, not least since the Union needs a Tory revival in Scotland (and a Labour revival in England).

In theory, the votes are there for Davidson. Nearly 700,000 Scots based their ‘no’ vote in the referendum on their attachment to the Union. They might have had concerns about unanswered economic questions too, but their primary motivation was their sense of themselves as being British as well as Scottish. Most of them would have voted ‘no’ even if they believed the SNP’s promise of jam and unicorns for all. These, then, are the unionist ultras upon whom Davidson is relying in May. If they won’t vote Tory, who will?

Anecdotally, some of them will. Labour’s commitment to the Union is palpably weakening and there are some former Labour voters who are now prepared to back the last remaining unimpeachably unionist party. Nevertheless, the electoral mathematics are unforgiving: the SNP continues to poll at 50 per cent and a divided unionist opposition is likely to be routed on polling day.

The pollsters are divided on the Tories. YouGov and Ipsos MORI predict a Tory recovery (that is, they think the Conservatives might win 18 per cent of the vote in May); Survation and TNS find no evidence of this, insisting that the Tory vote amounts to no more than 12 per cent of the electorate. The pollsters cannot explain this difference and they cannot all be right.

As recently as 1992, the Tories won 25 per cent of the vote in Scotland. That amounted to 750,000 voters. Even when, five years later, they lost their last 11 Scottish seats, they still managed to take 17.5 per cent of the vote. At no election since, whether it be for Westminster or the Scottish parliament, have they done so well. Last year the average Tory candidate won 7,358 votes.

Senior figures argue that it is misleading to focus on the awkward fact that the party’s share of the vote last year — 14.9 per cent, if you’re interested — was its worst ever performance. Many ‘natural’ Tory voters abandoned hopeless Tory candidates and supported Labour or Lib Dem candidates who were, notionally at least, better placed to stem the nationalist tide. There is some truth in this. I was one of those voters.

Nevertheless, the fact remains that the Tories won only 434,000 votes in Scotland last year. And that was in a Westminster election in which whatever remains of the Tory vote can be trusted to turn out and do their duty. Elections to the Scottish parliament are a different matter. The Conservatives opposed devolution in the first place and many a Tory died in the last ditch defending the unreformed Union. The party hierarchy accepted that since the Scottish parliament was not going to disappear, they’d best reconcile themselves to its existence; a hefty chunk of the Tory vote, however, has remained scunnered with Holyrood and would prefer it to disappear. In 1999 the Conservatives won 364,000 votes and 15 per cent of the vote; by 2011 so many Tories had died that the party was left with just 277,000 votes.

In theory Davidson should be able to do better than this. The problem is that her strategy’s success depends on voters altering their behaviour. Like Jeremy Corbyn, she must persuade people who do not ordinarily vote that this time they must vote.

The scale of the challenge is intimidating. If, as pollsters predict, turnout in May increases to above 60 per cent of the electorate, the Tories will need the support of approximately 500,000 Scots if they’re to win 20 per cent of the vote. In other words, nearly twice as many people will have to back the Conservatives in May as were prepared to at the last Holyrood election. I don’t suppose that’s an impossible scenario, but it still seems extremely unlikely.

The truth is that the Conservatives remain toxic in Scotland. Some 30 per cent of Scottish voters approve of the job David Cameron is doing, but barely half those voters are prepared to endorse Conservative candidates. The modernisation project has not been enough.

Moreover, in a world in which half the electorate will back the SNP, and Labour — even in its present crippled state — cannot avoid winning at least 20 per cent of the vote, it follows that once the minor parties have been accounted for, the Tories’ best possible result would see them winning approximately one in five votes.

All of this matters. The SNP are biding their time before calling another referendum. As Corbyn leads Labour into the wilderness, the Tories have a chance to govern from Westminster until 2030 even as they remain poisonous in Scotland. In those circumstances, many left-of-centre Scots might be prepared to risk a punt on independence. North and South Britain really would seem like different political cultures, no longer suited to cohabitation. That’s why Ruth Davidson and her valiant platoon of true believers remain important. But if even the twin advantages of a political realignment along constitutional lines and a widely admired leader cannot save the Scottish Tories, then one has to ask: can anything?