The prime minister is silent. Ed Miliband is a dud. Tony Blair is with the fairies. London is so desperate it has summoned Gordon Brown from his brooding lair and sent him north to save Scotland for the union. He has taken with him more gold than when Ethelred the Unready paid danegeld to the Vikings.

What has changed in the past month? The answer is poll-induced panic. London has reneged on its agreement to honour a policy purdah. With typical cynicism in all things local, it has spent a year promising – but never specifying – “devo max” and this has clearly not worked. Scotland has not been rattled by “project fear”. Being shot of Westminster’s devious machinations seems ever more appealing.

Now something has snapped. London says that Scotland, however it votes, can have autonomy that was beyond its wildest dreams a decade ago. We have gone overnight from devo max to “devo supermax”. A new “federation of Britain” is born, possibly including Wales and other provinces. Not since the disintegration of the British Empire has local discontent so traumatised the mindset of a London government.

If I were a Scot I would not trust an inch of this. Devo supermax looks full of holes. It is mostly about tax, and yet Scotland will not get the one economic game-changer, corporation tax, nor has London backed down on currency. It will not get full income tax flexibility, such as varying just the top rate. It will not get oil tax or VAT. Elsewhere it already has health, housing, education and police. No one wants to touch welfare benefits for fear of mass migration of the poor. What is left, short of full sovereignty?

Nor has London dared moot the other side of the equation, the 59-MP question. Devo supermax must cut drastically the number of MPs at Westminster and limit their voting power. The Treasury would also demand the subvention be “adjusted” for local revenue. Any such changes will in the short term be expensive for Scotland. But then London has been shouting this for a year, and Scotland has merely said “bring it on”.

The truth is that a good half of the Scots have had enough of English rule and want to see the back of it, period. When divorce is in the air, remorse, generosity, promises of good behaviour fall on deaf ears. This relationship is over. We can only hope they “stay good friends”.