I am told by a minister that the prime minister's big plan to keep Scotland in the union is to love-bomb it in the 18 months or so before Nicola Sturgeon introduces her referendum bill into the Scottish Parliament in late 2022 or early 2023.
That is consistent with my assumption that he knows he can’t stand in the way of a referendum without dishonouring the UK’s democratic heritage, and taking the whole UK to a very dark place.
As Gavin Barwell argues, it is hard for a British prime minister to argue that parliamentary votes don’t matter, whether at Holyrood or at Westminster.
Another part of Boris Johnson's strategy will focus on repeating the costs involved with independence
His least risky strategy is probably to work out how to win a referendum, rather than looking at constitutional and legal devices to stop it.
The UK will not survive if its member countries are in the UK because of coercion rather than the choice of their citizens.
Listen to our politics podcast, Calling Peston: