Andy Maciver is Director of Message Matters, and a former Scottish Conservative Head of Communications.

Napoleon said that history is a set of lies agreed upon. I wouldn’t go quite that far to describe the way that unionists remember the 2014 Scottish independence referendum campaign, but it’s not far off.

The closer one gets to London, the more widespread is the belief that the independence referendum was a runaway success. That it was a big win. I have heard some people even proclaim it a landslide. This is confirmation bias at its deepest.

To contextualise that, let us recall that unionists took the 30-point lead they’d had throughout my life, and limped home, having believed in the final few days that they might lose. And they might have lost, if Ruth Davidson hadn’t saved them. The outstanding Tory performer of the campaign, Ruth kept a clean sheet in goal while her Central defenders were having rings run around them.

Importantly, the repercussions of this confirmation bias are not isolated to the Scottish independence debate. There has been enormous collateral damage, particularly for Remainers: we should not forget that the people who brought us the pro-union campaign in 2014 decreed it to have been so brilliant that they lifted it out of its dusty box in the vault, and used it again in the EU referendum campaign in 2016. Contritium praecedit superbia.

How, then, did No blow its 30-point lead during indyref?

Downing Street and the Tory party, including, until recently, most of the Scottish Tory party, have never understood how to defeat nationalism. For decades, they have behaved tactically rather than strategically, perpetually reactive, hoping the next crisis never happens.

Since 1999, often badly advised by supposed Scottish experts, they have attempted to swim against the tide — not the tide of nationalism, but the very different tide of decentralisation, which they didn’t see coming and didn’t understand. The SNP — in the middle of a well-developed 15-year strategy — won a minority government in 2007, and then a system-breaking majority in 2011. Downing Street reacted with the Calman Commission and presumed that would fix the problem.

Then came indyref, a 2011 SNP manifesto commitment, which (at five-to-midnight) spooked a sleepy Downing Street. The panicked reaction was The Vow (which, if a new book is to be believed, Ruth vehemently opposed) and the Smith Commission which, again, Downing Street thought would fix the problem.

This is a destructive pattern of behaviour. Poll after poll, over the last decade, has shown that the “something in the middle” option beats the status quo and independence. Every time. But instead of taking a long-term (or even medium-term) approach, the Government opts for reactive appeasement: for giving the Scots just enough to keep them happy, but no more.

There are two ostensible justifications for appeasement — ideological and tactical. The ideological reason for appeasement is that many Conservatives are centralists. They oppose devolution, not just to Scotland but everywhere else. And that’s ok. It is a perfectly honourable ideological position, albeit not one with which I agree.

However, I do have a problem with the tactical justification for appeasement. It is rooted in a belief that each new power which is devolved is a win for nationalism and a defeat for unionism. It is this approach which led David Cameron and his Scottish advisers to dismiss the advice that some of their Scottish allies offered them in 2012, which was to make a meaningful, proactive “offer” to Scotland, foreseeing the trajectory of devolution and turning a No vote into a vote for something. The suggested “offer” was, ironically, similar to the post-referendum Scotland Act.

Downing Street believed they could maintain the 65:35 lead they had at the time by belligerently advocating the status quo. How wrong.

They could, however, have maintained that lead, and won by that distance, had they adopted this proactive approach. Nationalists did not do a particularly good job of pulling people in. On the contrary, it was the negative, unsophisticated unionist approach which failed to understand the aspirations of many Scots and pushed them towards nationalism.

This must change. The SNP’s Growth Commission was dismissed by unionists, as our political discourse demands, but that commission (led by the highly competent Andrew Wilson) represents an understanding by the SNP that an activist-led campaign dominated by the utopian left will never win.

Nicola Sturgeon has (in my view) a mandate for indyref2 (even if polls suggest Scots would rather she didn’t use it). A fresh Yes campaign, dominated by the adults in the room, would, if all the other stars were aligned, stand a decent chance of finishing the job that was started in 2014.

Nonetheless, the fate of the union still lies primarily in the hands of the unionists. This is about decentralisation, not independence. About power, not passports. There is no natural majority for independence in Scotland. It will only happen if unionists keep getting it wrong.