I make no apologies for the third post in a week on Scotland's referendum next week. A political story this big is rare. This time I want to consider Westminster's reaction to the episode. There is, of course, shock. The story has departed from its script. And with that shock comes recrimination. This sort of reaction is only human, of course - but the reactions miss the point. Britain, with its unwritten constitution, is uniquely vulnerable to this kind of sleepwalking disaster.
The most extreme reaction comes from John Major, who was Prime Minister from 1990 to 1997, at a time when the move towards devolution in Scotland developed unstoppable momentum. He is basically saying "told you so". He said that the whole devolution idea was a mistake, as he said at the time, and it is ending just as he forecast. Well, he is right that simply devolving power to Scotland (and Wales and eventually Northern Ireland) without considering the impact on the wider United Kingdom constitution was asking for trouble. But the resentment felt by the Scots over remote rule from Westminster was overwhelming. Something had to be done in the name of democracy. Besides, devolution seems to have been a success, for Scotland at least. Outside London and the South East Scotland is the most successful region in the UK. This kind of success is about a lot more than public subsidy. No doubt the oil industry has helped, but Scotland has seen the sort of economic dynamism that is sadly lacking in other regions of the country.
But Mr Major's is a lonely voice. Many more are saying that it was foolish of David Cameron, and the Scottish Secretary of the time Michael Moore, not to agree to Alex Salmond's wish for a three-way referendum, with "Devo-max" as a third option. But almost nobody outside the SNP thought that a three way referendum was a good idea at the time. I personally could not get my head around it. Referendums are a blunt instrument, not suited to complex questions. The whole thing looked like a sly manoeuvre on the part of the SNP to get more devolved powers, from which to launch a future bid to independence. If they had wanted Devo-max rather than full independence, they should have negotiated that explicitly.
A third line of recrimination, and the loudest, is against the No campaign. It is accused of being lacklustre, pessimistic and negative. It focused too much on the practical problems of separation. This is true. But negative campaigning is the Westminster way. Our politicians, advised by sophisticated professionals, find negative messages more useful than positive ones when it comes to campaigning for votes. They have two basic types of strategy: one is to rally the core vote, and the other is to swing marginal voters. Nothing rallies the core vote better than distrust of the other side. And swing voters are often cautious types who make up their mind on small things. This was certainly the view of the No campaign, which went for the second strategy, sensibly given the likely high turnout. Their polling showed that it was worries about the practicalities that was bothering the swing voters - so it addressed its energies to them. Such negative tactics worked triumphantly well in the referendum on the Alternative Vote in 2011; the No vote campaign was simply doing things the Westminster way. But that left the feeling that the argument for union was hollow at its core - something that besets Westminster's other campaigns.
Of course what the critics are unwilling to do is look at the wider picture, and recognise the vulnerabilities of the British system of government. Our highly centralised ways are bound to cause disaffection at the periphery. Devolving spending powers faster than taxation powers is not a stable solution to this: it just sets up a tension between the central government and the devolved one. And asymmetric devolution, favouring some areas over others, creates further tensions - tending to focus the tension in some areas rather than across the country.
There is a tried and tested method for containing and managing such tensions, that almost every other democracy uses. That is a written constitution, which defines the powers clearly at each level of government, and sets out clear ways of how the balance of these powers can be changed. The constitution usually has its roots in a process of consensus building at an important, nation-defining moment, giving it moral authority.
But Westminster dislikes written constitutions. It loves the flexibility of Britain's looser arrangements, whereby Parliament adopts the powers of a Renaissance monarch, bolstered by a sort democratic myth in place of the divine right of kings. And indeed such flexibility has its advantages. But it has vulnerabilities too. The constitution becomes a plaything of ordinary short-term politics; small changes are made that create further tensions that require more short-term changes. Or some constitutional problems are deemed too difficult, and not addressed, allowing very destructive tensions to build. Devolution to Scotland is a case of the former. Devolution within England is a case of the latter. The country sleepwalks into constitutional disasters. Scottish independence is one such potential disaster; departure from the European Union is another.
It requires some kind of national shock to give momentum to comprehensive constitutional change. The referendum in Scotland, whatever the result, is a big enough shock to set such a movement in motion. Time for a Constitutional Convention.