THEY thought it was all over, but it isn't.

The Scottish independence referendum, it turns out, wasn't a finishing tape but a starting gun. The national question may have been resolved for a generation, but Scotland is now in a race for home rule. History has been speeded up.

A last-minute electoral expedient, the historic "vow"from the three unionist parties to deliver devo max, has turned into something of immense constitutional significance. Political parties and civic groups will have to come together to write Scotland's future on the legislation that has to be before Parliament by next March.

That's a hell of a timetable, of course, and fraught with problems and pitfalls. It may seem absurd to try to write a new constitution for not just Scotland but by implication the entire UK in a matter of months. But sometimes these things happen. History throws up circumstances that force rapid change.

Think of Magna Carta - the 800th anniversary of which falls in June next year - which challenged absolutist monarchy and introduced the rule of law. Or the Declaration of Arbroath. Or the Glorious Revolution of 1688, which entrenched parliamentary democracy. We are fortunate in this country that our revolutions tend not to be bloody affairs that leave bitter divisions and enduring enmities. Perhaps, just perhaps, we can pull this off once again.

So, where exactly do we stand? Well, we have to start with the review under Lord Smith of Kelvin, noting that a member of an unelected chamber is hardly the ideal person to handle this important question of democratic accountability. Nicola Sturgeon showed real leadership (even before becoming leader) last week when she insisted that the SNP would not stand aloof from this process hoping that it would fail.

So, with the Scottish ­Government involved, the balance of power is already weighted to home rule. However, as Smith has recognised, this process requires much broader civic engagement than simply the political parties. The referendum marked one of the greatest popular democratic ­engagements in history, with 97% voter registration and an 85% turnout. The referendum brought people into active politics who had never even voted before.

Smith says civic Scotland will "have a say" in the review - but that is not enough. It has to be fully involved or the project will lack legitimacy. It was civic Scotland that created and sustained the campaign for a Scottish Parliament in the 1980s and 1990s and this must be reconstituted as a matter of urgency. But what is it?

Civil society encompasses all those extra-parliamentary groups with a decisive moral and political stake in the future of the nation. In the 1980s it involved the trades unions, the churches, local government, charitable bodies, think tanks as well as minor political parties that did not actually have parliamentary representation. This time, it needs to be broader still.

On October 25, various Yes supporters are convening a "way forward" meeting in Glasgow. This could be an opportunity to bring together new bodies like National Collective, that extraordinary coalition of artists, writers and performers who injected style and heart into the referendum campaign. There are also groups like Women for Independence and Business for Independence. This latter group, with more than 3000 members, brings together business people committed to social justice and political renewal. They will be rubbing shoulders with people from the Scottish Socialist Party, the Green Party and Radical Independence.

This looks as good a starting point as any. If other elements in Scottish civil society, like the STUC, the Scottish Council for Voluntary Organisations and church groups could be involved, this would pretty soon have a significant voice. A kind of pop-up constitutional convention. Groups like Reform Scotland and the Scottish Independence Convention, which have worked closely on the mechanics of home rule, would also have a very important input.

However, there are some very obvious dangers here. First of all, this could become an exercise in radical grandstanding and individual self-promotion. This is a very big movement and everyone will want to claim ownership of it. Radical left groups that have been in the wilderness for decades have suddenly found themselves part of the biggest movement they've ever seen. There are also radical nationalists who think the referendum was rigged and don't want to get involved with anything that might look like a compromise with the hated Westminster establishment.

The pop-up convention could collapse like Baked Alaska or become an endless talking shop, and that would do no-one any good. So, very quickly it needs to adopt broad principles that can command widespread support in Scotland and elect a small steering group that can inject these into the Smith review.

It's not for me to say, but were I asked to nominate representatives from civic Scotland I would put forward someone like the journalist Joyce McMillan, a highly respected figure who comes from no party but was a key figure in the steering committee of the Constitutional Convention in the 1990s. I would also nominate Henry McLeish, a former Labour first minister who has become one of the respected elder statesmen of home rule. They should be given wide freedom to negotiate in the Smith review and to demand formal inclusion. If the Liberal Democrats remain true to their federal principles then they could join with the SNP and civic Scotland to establish the founding principles of Scottish federalism.

It would be a mistake for the Smith review to become too detailed. Questions like the specific tax powers are too complicated to resolve before March. The legislation should look to establish firm principles.

First: sovereignty. As Gordon Brown proposed, there needs to be a declaration of sovereignty to entrench the Scottish Parliament as a state within a federal UK. This could be the start of a written constitution for the entire UK, but will have to be unilateral federalism for the time being, applying only to Scotland. Other regions of the UK must make their own way, but Scotland clearly can't wait.

Second: fiscal autonomy - the Scottish Parliament should raise the bulk of its revenue. This cannot simply mean devolving income tax because without other revenue, raising taxes like oil revenues, corporation tax and excise duty, it would be impoverished. The Parliament must be revenue-neutral on day one - in other words, no back-door £4 billion cut in the Barnett Formula.

Third: subsidiarity, as applied by Donald Dewar in the 1998 Scotland Act. There are numerous anomalies such as broadcasting and welfare measures like housing benefit that should never have been reserved to Westminster and need to be in the hands of the Scottish Parliament.

Now, critics will say that this is independence by the back door; the Nationalists trying to win the referendum by other means. It is not - this is federalism. The trouble with the constitutional debate so far is that it hasn't yet looked seriously at how federalism actually works, even in highly centralised unions like the USA. Oregon, for example, has widespread economic powers and even abolished VAT/sales tax in favour of income tax as a means of financing its activities, which include the highest minimum wage in America.

Federalism is much more stable than the fiddly forms of disingenuous devolution that the three parties have proposed. It works well in countries like Australia, Canada and Germany - we should know because it was Britain that introduced federal constitutions in these countries. If the UK parties really want to see a stable UK, they should adopt a formal separation of powers with defence, foreign affairs and monetary policy in Westminster and allow Holyrood, largely, go its own way.