Lord Hennessy is a historian, academic and cross-bench peer.

Scotland remains the constitutional question. As Lord Smith of Kelvin made plain in his report, the consensus he crafted from the five-party discussions could be just a way-station to either what one might call Devo-Max-Max, or to complete independence. The ‘Neverendum’ syndrome, as the Canadians came to call their sequence of referenda on the Quebec question, could develop here. Just think of the fuse the following outcomes would light once more under the United Kingdom:

  • 30–40 SNP members elected to the Westminster Parliament on May 7.
  • The SNP win another outright majority in the Scottish Parliament in the Holyrood elections of May 2016, with another referendum as the party’s top election pledge.
  • At some point between 2016 and 2020, the UK as a whole votes in a referendum to leave the European Union while the vote in Scotland is strongly to stay in.

In my judgement, that would mean a second independence referendum in the 2020s, which could well go the way of separation.

In other words, not only is Scotland likely to remain in a condition of political inflammation (even without the European ingredient), but the survival of the UK in its present form remains a live question.

Let us for a moment assume that the new, Smith-shaped settlement for Scotland is in place with all the necessary legislative underpinning in the spring or summer of 2016. There exists the possibility that economic disturbance of a serious kind (Eurozone or global-recession induced or something less foreseeable) will pummel the UK by 2020 if not sooner.

Such an occurrence could well apply the economic and fiscal stress test to the new Anglo-Scottish financial membranes that Alistair Darling has spoken of. The global economy can be a thing of swiftness and brutality; it would be both blind and deaf to the needs and sensitivities of a United Kingdom still striving to make its new internal deal work.

By then new deals could well be under negotiation on further devolution to Wales and Northern Ireland and on decentralisation within England. And the very institution in which the high policy will play out and in which the needed legislation shaped – Parliament – could well be in a state of reconstruction.

Will we see the formation of a surrogate English Parliament within the existing House of Commons? Will blueprints be in production for a House of Lords completely remade as a Senate for the Nations and Regions, with its members either directly elected or indirectly elected by the parliaments, assemblies, regions, city statelets, clusters of counties and towns – or whatever patchwork quilt emerges to clothe the English landscape? And will we achieve what the philosopher Onora O’Neill, Baroness O’Neill of Bengarve, called ‘Devo-coherence’ with such a likely variety of authorities?

Other institutions may be morphing as a result of this picture of multiple, rolling change. Can a unified civil service be sustained under devo-max for Scotland, with easy inter-changes of official talent between all parts of the kingdom? Robin Butler – Lord Butler of Brockwell, the former Cabinet Secretary and Head of the Home Civil Service – described the unified civil service as ‘one of the bits of glue that holds the kingdom together just like the Armed Forces and other services of the Crown’ adding that he couldn’t see why the tradition of serving different administrations shouldn’t continue under devo-max. ‘We’re used to conflicting loyalties’, he said when I talked to him for The Kingdom to Come.

Another institutional worry could be that the Supreme Court, which arbitrates in disputes about powers between the devolved administrations and Westminster/Whitehall, might become politicised if devolution-related business rose as a proportion of its workload. Lord Hope of Craighead, its former Deputy President, thinks that can be avoided:

“The Court looks at the language of the statute under which the issue arises. And it [will be] interpreting the statute and applying it in the way that the Court has always done – and that’s not a political exercise, it’s a judicial exercise. And the individuals who are sitting there are chosen entirely independently of government now and there’s no question of them having a political angle on this at all. So I would hope that people wouldn’t try to politicise it.”

So do I.

Is there lurking here a great opportunity to break the habits of a national lifetime and go for a written constitution to pull the threads together? Graham Allen, the Labour Chairman of the House of Commons Political and Constitutional Reform Committee, has led his colleagues through the possible ways of doing so if Parliament and people so wished.

And the President of the Supreme Court, Lord Neuberger, touched on the possibility last October. ‘I think’, he told a gathering of lawyers in Bangor, ‘it is not inappropriate to raise the question, and I emphasise that it is genuinely no more than raising the question, of whether the time has come for the United Kingdom to have a constitution’.

Lord Neuberger rehearsed the pros and cons including the argument that:

“We have managed very well for many centuries without a constitution, so why mend it if it ain’t broken? It is beguiling to invoke the existence of successful constitutions of other countries, but it is plain that what works very well in one country may not take root successfully in another. The British constitutional system has developed on a piecemeal basis, and to impose a written constitution on such a system is, some may think, a questionable exercise: it could be said to risk forcing an inherently flexible system into an artificial straightjacket.”

‘But’, he continued, ‘there are powerful arguments the other way.’

“First, we are in a new world whose increasing complexity appears to require virtually every activity and organisation to have formal rules as to how it is to be run and to work, and there is no obvious reason why that should not apply to the most important organisation of the lot. Secondly, we are now in what to some people might seem to be in an unsatisfactory position with an international treaty, as interpreted by an international court, namely the European Convention on Human Rights, acting as a semi-constitution.”

(It’s worth noting in passing that at the 2014 Conservative Conference, David Cameron pledged to establish a new British Bill of Rights.)

Lord Neuberger summed up in a long but beautifully balanced paragraph:

“We have a proud and successful history with a pragmatic, rather than principled, approach to law and legal systems, and we have managed pretty well without a constitution. But times change, and the fact that we managed well without a constitution in a very different world from that which we now inhabit may be a point of limited force when applied to the present. So long as things remained much the same, the argument based on the status quo was hard to resist. However, if, and it’s a big ‘if ’ which is ultimately a political decision, our system of government is going to be significantly reconsidered and restructured, there is obviously a more powerful case for a written constitution. Writing a constitution may help focus minds on the details of the restructuring, and, once the reconstructing has occurred, a new formal constitution should provide the new order with a clarity and certainty which may otherwise be lacking. On the other hand, it remains the case that grafting a written constitution onto our pragmatic system would almost inevitably involve something of a leap in the dark, and many people may fear that it would turn out to be a classical example of a well-intentioned innovation which had all sorts of unintended and undesired consequences.”

In my view, it’s highly unlikely that an overarching written British constitution will coagulate out of the kingdom to come, however first-order and fundamental some of the questions we face. The Scottish settlement will have its statute. There is a strong possibility that Commons procedure will be adapted to facilitate some version of EVEL. There is, too, a definite likelihood of a convention after those developments are properly underway to, as it were, mop up the rest and fashion an overarching constitutional settlement that captures the multiple changes as coherently as possible.

For me, such a constitutional convention must approach its task with a particular state of mind about the need to enable both mutual flourishing and a capacity for the UK to think and act together as a Union, as a collectivity amongst all the devolution and decentralisation. It’s crucial for the shared future of those who live in these islands that we should not Balkanise ourselves, in either structural terms or in our minds and hearts – for that way lies friction, fragmentation and discord.

Never before in recent times have constitutional possibility and peril jostled together quite like this. Despite the 55/45 result in the Scottish referendum, there is more uncertainty lying upon the kingdom to come than at any peace-time moment in the memories of the Queen’s subjects. The British constitution, with its mix of statutes, codes, custom, precedent and tacit understandings, may still baffle but it has ceased to bore. Refashioning it successfully and enduringly is going to take immense care and thought, plus a high level of consensus within the political parties and between the constituent parts of the kingdom. With time, intelligence and forbearance all round, it can be done in a way that serves the needs of the generations to come. If it is botched, they will curse us – and rightly so – for they will have to live with the consequences.

This article is a chapter from Lord Hennessey’s book “The Kingdom to Come: Thoughts on the Union before and after the Scottish referendum. (Haus Publishing.)