IT was a grey dawn that broke over Holyrood on the morning of September 19, 2014. Yes campaigners trooped in the rain to Edinburgh's Dynamic Earth exhibition centre for what many had hoped and believed would be a victory celebration. It felt more like a wake.

Alex Salmond put on his brave face and declared that the referendum result was a triumph for democracy that vindicated the decision to call it in the first place. Not many believed him at the time.

It seemed as if the Union had won a convincing victory. This was the first occasion on which Scots had been given a democratic choice on whether or not to remain in the Union, and they'd voted to remain.

But one year on there can be little doubt that Salmond's counter-intuitive celebrations were largely justified. However, he was gracious enough to realise that he had to depart the political scene so that Scots could see the result more clearly.

Scotland really had “changed, changed utterly” as he put it in his resignation speech. To the immense frustration of the victorious Unionists, the losers seemed to win it all.

The membership of the Scottish National Party more than quadrupled. Nicola Sturgeon became the people's champion, addressing stadium-sized audiences across Scotland. Scottish nationalism became the new normal in areas like Glasgow, which had been Labour strongholds for a century.

The independence referendum of 2014 was the most transformative political moment in Scotland in 300 years. It marked the beginning of the end of the Union of 1707, the consolidation of a distinct Scottish political culture, the end of Labour's political dominance of Scotland. It also marked the decline of the conventional UK media as a shaper of mass political opinion.

Everything changed even though, paradoxically, things remained outwardly the same. Scots remain citizens of the United Kingdom and Westminster retains ultimate sovereignty over legislative affairs. Scotland's MPs are not engaged today in complex negotiations over separation: bargaining Trident against debt, carving up the BBC, dividing military assets.

An independent Scotland is not knocking on the door of the European Union; the Bank of England is not trying to calm febrile financial markets; the Queen is not insisting that Britain still remains a going concern.

But this is only the shallow surface of continuity. Scottish civic society crossed a psychological rubicon in the course of that extraordinary political campaign, in which an unprecedented 97 per cent of Scots registered to vote and 85 per cent actually turned out on the day – the highest turnout since the achievement of adult universal suffrage in Britain.

Some 1.6 million Scots voted Yes after a campaign in which independence was portrayed as tantamount to economic suicide. Whole sections of Scottish society, mainly but not exclusively working-class, were persuaded for the first time that voting actually mattered. (Shamefully, 11 Scottish councils used the enhanced voter rolls to pursue working-class Scots for poll tax arrears going back 25 years)

Just about everyone recognised at the time how significant this campaign was – even most Unionists. You could not escape the referendum effect – it was everywhere: in town halls, pubs, clubs, dinner tables and of course on the streets. It was the most intense period of earnest political disputation that I have ever experienced in 30 years of covering politics.

Previous referendums were never like this. The 1979 devolution referendum was a non-starter. Neither Nationalists nor Unionists could raise much enthusiasm for a toothless Scottish assembly with no powers to speak of and an incoherent remit.

Nor, despite the dramatic result, did the 1997 referendum bear any comparison to 2014. Scots voted by a margin of three to one to set up a parliament with tax-raising powers, but there was no great popular enthusiasm on the streets. There was little sense of occasion.

It was as if these referendums were trial runs on the road to the Big One. The year 2014 was when Scots started to get serious about self-government. It was an existential choice, and though Scots pulled back from actually leaving the UK, they made clear their determination only to remain within it under very altered terms.

This was confirmed by the tsunami general election of May 2015 – the devastating aftershock to the referendum result. Just as a real tsunami is the tidal aftershock of an oceanic earthquake, the crushing Nationalist victory in May was a measure of the subterranean change that had taken place in Scottish society.

Some 56 independence-supporting MPs out of 59 now sit in the House of Commons, after the most dramatic general election swing – averaging 30 per cent – in Scottish or UK history. Scottish Labour lost 40 out of its 41 MPs, bringing to a crashing end a century of electoral dominance.

Recent opinion polls by Ipsos Mori and TNS confirm that a majority of Scots would now vote Yes to independence were there another referendum. The margin is small but significant. It does not necessarily mean that the result would be any different, but it does confirm the paradigm shift.

So why didn't Scots vote Yes when they had the chance? Why vote on such a massive scale for the party of independence less than a year after rejecting independence? I think the answer to this is a combination of economic realism, understandable caution and uncertainty about the nature of what was being offered.

It was made very clear to Scots during the referendum campaign that independence would be fiercely opposed. The Tory Chancellor, George Osborne, promised to deny Scots the use of the pound if they voted Yes. This would have undermined trading relations between Scotland and its major trading partner. In response, the Scottish Government threatened to renege on its share of the UK national debt. Wars have begun over less.

The governor of the Bank of England, Mark Carney, made clear that an independent Scotland would be regarded as an alien nation. Effectively, it could not expect the kind of financial co-operation that was extended to former colonies of the British Empire. In the 1960s, bank officials visited newly emergent African nations urging them to stick with sterling.

Financial institutions like RBS and Standard Life threatened to relocate their HQs to London encouraging a flight of funds. Big companies like Aggreko, BP warned that they would have to review their investments in Scotland.

The European Union President, Jose Manuel Barroso, said an independent Scotland could not to expect to remain in the EU, even though Scots had been subject to European Union law for 20 years. President Obama, anxious perhaps about the future of Nato bases, backed the Union.

Faced with these threats to Scotland's economic livelihood, and the prospect of diplomatic isolation, it was perhaps remarkable that so many Scots actually voted Yes. Day by day the press reported the latest “blow to Salmond”. Scots were advised that voting Yes could cause a second Great Depression; halt the discovery of a cure for cancer; leave Scotland vulnerable to terrorism.

The Sunday Herald was the only newspaper – daily or weekly – that actually supported Yes in the referendum and tried to inject an element of balance. The BBC did its best to appear neutral, but couldn't avoid being influenced by the sheer weight of Unionist propaganda in the press.

Better Together insist they were just being realistic about the dangers of independence. But to many it felt like intimidation. Most observers now accept that the negativity of the Unionist campaign was counterproductive. It undermined faith and trust in the Union and antagonised many voters.

The referendum turned into a near-death experience for the UK. Better Together began with a commanding lead of 70 per cent to 30 per cent, which most regarded as unassailable. Yet it all but evaporated. On September 9, with 10 days to go, YouGov reported that Yes were narrowly in the lead.

The Westminster establishment descended into panic. It took the combined efforts of all three UK party leaders, backed by the former PM Gordon Brown, and the massed ranks of the London-based media, to haul Scots back from the brink. After months of veiled threats of economic isolation, suddenly it was back to promising the earth.

The infamous “vow” in the Daily Record, signed by Cameron, Clegg and Miliband three days before the ballot, did not actually mention federalism or even devo-max. But the message was clear: vote No, and there will be more powers for Holyrood. “Nothing is off the table,” said David Cameron.

Whether that vow was honoured is a matter for history. It is however a matter of fact that not one of the SNP's amendments to the subsequent 2015 Scotland Bill was accepted by the UK Government. The Barnett Formula is to be phased out as Scotland is given greater tax-raising powers. But the prospect of devo-max, let alone a federal United Kingdom, seems as remote as ever.

The UK press remains unreconciled. Press commentators like the Daily Mail's Chris Deerin insist that Scotland had simply “gone mad” during and after the referendum. Others dismiss it in retrospect as a huge distraction from real issues – an essentially emotional event, rather like a religious conversion, or a “cult”.

Perhaps there was a secular echo of the evangelical mass “awakenings” that occurred fairly frequently in Scotland in the 18th and 19th centuries. One prominent figure described it, only half joking, as Scotland's summer of love.

However, this wasn’t about religion and it wasn’t about identity either, as many metropolitan commentators have tried to define the referendum experience. If there was a passion here it was a passion for politics, and for the art of the possible. Which is why, I believe, many Scots voted No because of the risks of economic dislocation.

But there was no overt hostility to English people; no mawkish celebration of Scottish culture. There will always be disagreement about this, of course. This weekend we have been reminded how the novelist JK Rowling was abused by cybernats, and bow brave Jim Murphy risked life and limb before egg-hurling apostles of hate. It was a bitter and divisive struggle according to some.

A moment's reflection on the bloody history of the national question in Ireland should surely be enough to dispel this kind of wilful exaggeration. Scotland's referendum campaign was one of the most peaceful and law-abiding independence struggles in modern history. No bullets were fired; no heads broken; not a pane of glass shattered.

Nor did Scottish voters allow their debate to be hijacked by poisonous trolls on the internet. Sections of the Scottish and UK press tried to taint the independence campaign by association with so-called cybernats. But in the end they only did damage to themselves as Scottish voters simply stopped listening.

Mistakes were certainly made in the supposedly non-party Yes Scotland and there were concerns about the SNP's dominance of it. There is a lively dispute over Alex Salmond's reluctance to consider alternatives to the policy of a common currency with rUK. Jim Sillars says that was “a gift” to Better Together.

However, it seems most unlikely that the middle-class and older Scots who voted No would have been reassured by the promise of a separate Scottish currency, or “Panamisation” as it was called. The majority voted No out of concern for their own and Scotland's financial security.

Older voters, who remember the aftermath to the Second World War and the great reforming UK governments that created the welfare state and the National Health Service, were not convinced of the need for independence. Britain still meant something to them.

Moreover, there was a studied vagueness in the Scottish Government's lengthy White Paper, Scotland's Future, about what independence would actually mean in practice. The Queen, the pound, the BBC, the armed forces, energy utilities, even the National Lottery were, it seemed, to continue. But if so many decisions were to remain in Westminster after independence, why withdraw Scotland's democratic representation from there?

The idea of formal independence is anyway a very novel concept for most Scots. For most of the last 300 years, Scotland, unlike Ireland, remained an enthusiastic partner in the Union. It is only really in the last two decades that ending the Union has been debated seriously here.

The SNP was a party on the very margins until the coming of Alex Salmond. But now it is the dominant force in Scottish politics, and likely to remain so. The debate is not about whether, but when, the next independence referendum will be held. The former head of Yes Scotland, Blair Jenkins, believes it could be as early as 2021.

Independence of course is not inevitable, and no-one should take Scottish voters for granted. Many Yes supporters had significant concerns about aspects of the independence agenda which need to be addressed before repeating the exercise.

It may also be possible that a revised and reformed Union could continue in some form. After all, the 1707 Treaty was at root merely a declaration between two countries that they would co-exist in peace and co-operation.With goodwill, a new Union could be forged based upon a recognition of Scotland's implicit sovereignty.

But what is beyond doubt is that there can be no going back to the old, somnolent, apathetic, Westminster-dominated Scotland. Whether the constitution recognises it or not, Scotland is now becoming an independent country.