This article was originally featured in The Herald
Scotland's No vote last September was meant to draw a line under the UK's constitutional debate. Fat chance.
What we have seen instead is a constitutional chain reaction let loose by pro-Union politicians making short-term calculations with little thought to their longer term consequences. And just like chain reactions in the physical world, this political chain reaction is unstable, unpredictable and uncertain in its outcomes.
It all started with YouGov's September 5 poll that put the Yes side ahead at 51:49. No other credible poll had put Yes ahead. A host of others published in the next couple of days confirmed we were in a neck-and-neck race. The result? Panic.
So three days later Gordon Brown, with the blessing of David Cameron, Ed Miliband and Nick Clegg, declared that, from September 19, the pro-Union parties would produce agreed proposals on additional devolution for Scotland by the end of November, with these leading to draft legislation by the end of January 2015, so that whoever won the May 2015 UK General Election would be in a position to enact that legislation. All this was reiterated, this time by the three party leaders directly, in "The Vow" of September 16.
Of course, the pro-Union parties could have done all of this months beforehand. They each had worked-up proposals to hand, produced by the special commissions each had set up. It wouldn't have been hard to produce a joint document. But they didn't. They were forced into action in a last-minute panic.
That panicked reaction worked as a short-term tactic. Our polling team at the University of Edinburgh found that the pledge to give Scotland additional devolution was one of the key factors in firming up the No vote as referendum day approached. But, as many in the Labour Party may now be wondering, at what cost?
Only since the referendum has it become clear how much Labour in Scotland was damaged by being part of a No team in which Alistair Darling (and, at the end, Gordon Brown) shared the headline billing with David Cameron. Beyond the 20 per cent or so of Scots who might vote for them, the depth of hostility to the Conservatives among the other 80 per cent is one of the starkest and most enduring features of UK politics.
Labour is feeling this in the slew of polls anticipating what will happen in next May's Westminster election in Scotland. If they are to be believed - and even after Jim Murphy's election as the new leader - Labour could face something close to a wipeout at Westminster. Contrast that with the rock star adulation experienced by the new First Minister, Nicola Sturgeon, in her tour of Scotland's concert venues in November.
So the party that provided the backbone of the No campaign has ended up looking like the loser in Scottish politics, and the party whose constitutional cause was clearly rejected in September has the air of the winner, reinvigorated in its constitutional ambitions.
It is not just in Scotland that the game has changed. When David Cameron spoke outside Number Ten on September 19, he followed up The Vow by launching the Smith Commission. And the Commission worked at breakneck pace to deliver agreed proposals on further devolution for Scotland, notably in the fields of tax and welfare, by November 27.
But, while on the doorstep of Number 10, Mr Cameron also announced he was opening up a new flank in the constitutional debate. He had, he told us, "long believed that a crucial part missing from this national discussion is England" and that English Votes on English Laws (Evel) needed to be introduced in the House of Commons on the same schedule as change in Scotland.
It would be fair to say he had shown no obvious sign beforehand of his "long belief" in Evel. Cameron's conversion was a short-term, tactical response to developments in Scotland, another stage in the chain reaction.
Gordon Brown and Alistair Darling saw this as an anti-Labour tactic. Indeed it is. Evel would mean that MPs from Scotland would have at best a reduced role in deciding laws on England-only matters. Labour has most of Scotland's MPs. They would not count under Evel, making it more difficult for Labour to secure a stable majority for all business in the House of Commons (though this may become an academic point if Labour is indeed replaced by the SNP as Scotland's main party at Westminster next year).
But there was a different tactical point than dissing Labour at the forefront of the Prime Minister's mind when he made his Evel announcement. He needed to mollify his own party's right wing in England, which was not convinced about more devolution for Scotland, and was worried by competition for English votes from Ukip.
As our research has shown, Ukip is England's nationalist party. Alongside their disdain for the EU and hostility to immigration, Ukip supporters overwhelmingly support Evel (and oppose what they see as the cushy deal Scotland gets from the Union). They are predominantly English, not British, by identity and are more likely than anything else to be ex-Conservatives.
Even before the referendum there were signs of concern on the Conservative right that concessions to Scotland made the party vulnerable to this new English nationalism. Boris Johnson complained in mid-August that "for no reason we are promising the Scots more tax-raising powers ... what has England ever got out of this devolution process?" By September 15, John Redwood provided the answer: "We English MPs are very happy to vote through more powers for Scotland ... But our price is no more Scottish votes on English issues in the Parliament."
So now, with William Hague's publication of his Evel options paper on December 16, Evel is firmly on the agenda. But there is not much sign of forethought as to how Evel in practice might work. The commitment to Evel is not because of deep belief that it is right, but because of the short-term tactical needs of the Conservative Party.
And remember: those needs emerged as a consequence of "The Vow", itself a short-term tactical response to the Yes side nudging ahead on 5th September. Who knows what unanticipated consequence will follow on as the debate on Evel unfolds.
There is no constitutional big picture that has a vision of overall balance of the different parts of the UK. What we are watching is constitution-making on the hoof. It is rushed, rudderless and increasingly divisive. It sets party against party, with Labour in constitutional battle with the SNP in Scotland and the Conservatives in England. And it sets nation against nation, with debate in England increasingly directed against Scotland.
Where it will all end is unclear. But we know of one possible outcome from chain reactions in the physical world: meltdown. How ironic it would be if Mr Cameron, perhaps already eyeing his place in history as "the PM who saved the Union", ends up being known as the PM who set in motion the chain of events which fatally weakened that same union.