In the days after 5 September, when a poll put Yes Scotland ahead for the first time in the referendum campaign, we witnessed something remarkable, even unprecedented, in recent decades – the British political elite scrambling in panic as they belatedly understood that the ground beneath them was moving and drastic action was required. In response they began making policy on the run, hastily promising further powers to Scotland and mobilizing whatever forces they could, especially big business, to help pull the Union back from the brink.

Had Scotland voted Yes, David Cameron would surely have been forced to resign as the prime minister who lost Scotland and presided over the break up of Great Britain. Ed Miliband, the Labour leader, might well have been forced to stand down as well in what would have been an ensuing constitutional crisis.

In the event, Scotland narrowly voted No and now an opportunity exists to reconfigure the multinational United Kingdom to the benefit of all of us living in these islands. Clearly the status quo is unacceptable, not only to the large number of people in Scotland who voted for independence. Our present constitutional settlement is not merely unacceptable; it is broken, as David Cameron acknowledged when he spoke outside Downing Street once the final result was known. Whether the UK is reconfigured as a fully federal or quasi-federal state, something fundamental has to change and will change. We are entering a period of profound constitutional upheaval.

It will not be enough to offer more devolution to Scotland as the three main party leaders did in the final, desperate days of the campaign, however inchoate. The question of devolution in England has to be addressed as well. Cameron spoke of the need to address the West Lothian question – English votes on English laws - but should we have an English parliament or perhaps the introduction of regional assemblies under a new federal structure? Cameron did not mention this but the House of Lords needs to become a fully elected second chamber or be abolished altogether. What too of further powers for Wales and Northern Ireland? These are momentous times.

One of the most startling interventions during the final days of the campaign was made of course by Gordon Brown, the former Labour prime minister, who returned dramatically to frontline politics as the cross-party Better Together campaign floundered. In a series of speeches, consciously echoing Gladstone, he promised “home rule for Scotland”, even if there was no consensus on what was actually being offered and how it would affect the other nations in these islands, not least England.

At times it seemed as if the former Labour prime minister was dictating policy to his successor, who, because of the decisive defeat of the Conservatives in Scotland, was rendered virtually mute during the long campaign and was left at the end pleading plaintively with Scots “not to go”. It was desperate stuff and one expects Cameron’s party to punish his weakness in the months ahead.

What we witnessed in Scotland during the campaign, especially in those final weeks, was an extraordinary democratic awakening. An ancient nation was asking fundamental questions about identity, purpose and sovereignty, and people were as animated as they were well informed. The SNP operates a formidable and disciplined campaigning machine but Yes Scotland amounted to much more than Alex Salmond and his happy band of followers; it was a broad, vibrant coalition of pro-independence groupings.

What the referendum campaign demonstrated was that, in the right circumstances and when people believe that something truly significant is at stake and that their vote matters, they care passionately. At a time when fewer and fewer of us are members of political parties, nearly 4.3 million registered to vote, 97 per cent of those eligible. Overall turnout was 86 per cent, testament to a nation’s engagement and a direct challenge to a broken political system.

But how now to capture and harness the energies that were unleashed during a referendum campaign in Scotland that shook the foundations of the British state, stunned a complacent elite and came so close to shattering the 307-year-old Union?

And this much I know: unless there is far-reaching constitutional reform, there will be a second Scottish independence referendum before too long.