The idea that Nicola Sturgeon was on the point of throwing caution to the wind and plunging Scotland into another independence referendum was considered far fetched until only very recently. But in the last few weeks there has been growing confidence in the First Minister’s circle that the strategy being pursued by Theresa May was playing into their hands.

For the nine months since the referendum, Ms Sturgeon has plotted a carefully judged course from which she’s never deviated, always aiming to lead her adoring activists to the point when Monday's announcement could be put off no longer, while at the same time constantly declaring that she was a victim of an intransigent Prime Minister in Westminster.

Despite their words to the contrary, the losing separatists have never accepted their defeat in the 2014 referendum, even if Nicola Sturgeon insisted it was a “once in a lifetime” event. They...