In Scotland the traditional cure for a hangover is a can of Irn-Bru – the nation’s favourite bubble-gum flavoured soft-drink. And it is very likely that today, Irn-Bru owners AG Barr will be doing a brisk trade. While the majority of the Scottish electorate will be breathing a sigh of relief that the Union remains intact, we can also imagine that 45% of Scots will be nursing a psychological hangover today as their dreams of a sovereign nation have been dashed.

The Church of Scotland was the first to recognise the nation’s emotional fragility when the Rt Rev John Chalmers advised Scots to go out and take a ‘selfie’ with someone from the ‘other side’. His concern – and that of many others – was the need for reconciliation in a two-year long campaign that has energized but also divided the people of Scotland. Friends, colleagues, and families have come to (usually polite) loggerheads on how best to secure the best interests of their country. Now is the time, – as Alistair Darling, Alex Salmond and all of the party leaders have stated – for Scotland to come back together again to achieve the change it so clearly wants.

For the failure of the ‘Yes’ side is by no means an end to the national question in Scotland. Instead, it is the beginning of the national question in the UK. The groundswell of political engagement in Scotland over the last two years has inspired ordinary folk across the rest of the British Isles to ask the same questions as people north of the border: how can we achieve a more democratic, equitable society? How can we end poverty, eliminate discrimination, follow a more sustainable path of economic development?

And thus the Scottish independence referendum has opened up the Pandora’s Box of territorial identities, politics and interests in the UK. What hold this country together? What is Britishness? And how can we make Britain a more tolerant, just, democratically accountable, and recognisably multinational place to live?

David Cameron’s speech this morning gave some comfort – but also raised some thorny issues – for those people across the whole of the UK seeking change. In it, he assured those Scots that may be “sceptical” of his last-minute vows to enhance the powers of the Scottish Parliament that “we have delivered on devolution and we will do so again”. Cameron is under significant pressure – from Scots voting Yes as well as Scots voting No – to live up to the promises that he, and the other UK party leaders, Ed Milliband and Nick Clegg, made in the last few days of the referendum campaign.

We cannot have a repeat of 1979 – when the first devolution referendum in Scotland failed and the promises of further constitutional change from UK leaders never materialised. We also cannot follow the model of the failed 1980 and 1995 referendums on independence in Quebec, when Canadian federalists swept their vows of stronger powers for Quebec under the constitutional rug.

But perhaps the biggest difference with Quebec is that Cameron not only faces pressure from the Scots for further constitutional change. He also faces pressures from civic society across England, Wales and Northern Ireland, and from his anti-independence allies, the Labour and Liberal Democrat parties, to initiate far-reaching constitutional change that transforms the very nature of British democracy.

The question of England – or as my colleagues at Edinburgh call it, the dog that finally barked – is now firmly on the table. Cameron’s announcement that he will seek to implement the McKay Commission’s recommendation of ‘English Votes for English Laws (EVEL)’ will go hand-in-hand with reforms to empower the Welsh Assembly that were foreseen in the Silk Commission.

Some English voices have taken this one step further, asking for the devolution of powers to the regions of England (as was first attempted in 2004), the strengthening of the London Assembly on a par with Scotland, the creation of a separate English Parliament, and even the dreaded ‘f’ word: federalism, whereby we would see the abolition of the House of Lords and the creation of a second territorial chamber.

Of course, there are several variables that may unravel the constitutional ‘chain reaction’ (as my colleague Charlie Jeffery put it) which the failed Scottish independence referendum has set in motion. The first is the possibility that the pledge for further powers for Scotland, for starters, may come apart at the seams. While the pro-UK party leaders may have agreed on an accelerated timetable for agreeing enhanced powers, they have not agreed on what those powers will be.

Each of the parties – Labour, the Lib Dems and the Conservatives – published their reports on further devolution over the last few months and while there is some overlap, there are also major differences. Thus the Conservatives and Lib Dems want Scotland to have full control over income tax; Labour does not. Labour and the Lib Dems wanted Scotland to have more control over welfare policy, especially attendance allowance and housing benefit; the Conservatives do (or at least did) not. These are serious disagreements that will take some time to reconcile.

Which brings me to the proposed timetable for constitutional change. As my colleague Nicola McEwen astutely observes, the faster schedule for agreeing new powers seems completely unfeasible. A government White Paper by the end of November and a new Scotland Bill by January? And only one month for ‘engagement with civic Scotland’? One wonders if Cameron et al were mixing something with their Irn-Bru when they came up with this plan.

The Scottish Constitutional Convention, as we’ll recall, took almost a decade to come up with a blueprint for the Scottish Parliament, achieved through agonistic, deliberative democracy. The Calman Commission on Scottish Devolution took two years of widespread consultation to issue a final report, and another three years before the recommendations were incorporated into the Scotland Act 2012. Do the pro-UK parties really believe that we will initiate and conclusively finalise a proper, thoughtful, consultative process of radical constitutional change within three months?

The likelihood of a ‘fudged devo-max settlement’ as Patrick Dunleavy thoughtfully puts it, in such a restricted timetable, is quite high. Especially as any ‘constitutional convention’ – as Douglas Alexander would hope to see – would not only have to deal with the complex issues of Scottish devolution, as well as Welsh and Northern Ireland devolution, but also the more complicated issues of English governance.

Whatever the outcome of the discussions for change over the next few months, one thing is clear. Ironically, the decision of the majority of Scots to vote ‘no’ yesterday may result in even more radical constitutional change to the UK state than the arguably more simple secession of Scotland. Put another way, keeping Scotland within a radically decentralising or federalising Union is a more complex act of multi-level governance than splitting the UK into two parts.

One wonders whether the UK Party leaders (potentially with the exception of the federalism-loving Lib Dems) really thought through the implications of their belated ‘vows’ to enhance Scottish self-determination for the functioning of the UK state.

However, one burning issue should focus the parties’ minds and commitments to real constitutional change.

If the UK parties are unable to agree on the future powers of each nation that makes up the UK state, and civic Scotland (and indeed civic England, Wales and Northern Ireland) are excluded from what looks like another top-down imposition of change, the spectre of independence may loom large once more.

And this will be especially salient if, in the ‘worst-case scenario’, the Conservatives win the general election in 2015 and manage to pass their referendum to exit the European Union. In this case, many of the left-leaning pro-EU Scots that ended up tilting the result towards ‘No’ yesterday may have good reason to think again.

Please note that this blog originally appeared on the Political Studies Association blog on 19 September 2014.