Boris Johnson’s failure to rebuke Donald Trump for his unpresidential attacks on the serving British prime minister and our US ambassador show that he takes for granted he’ll be the next PM, despite his insistence on the ITV debate last night that it would be presumptuous for him to do that.
He is looking beyond the short-term attraction of being seen to stand up for Britain against a bullying US, to the relationships that he thinks will determine whether his early weeks in office are forceful or farcical.
According to those closest to him, this isn’t just kowtowing to the most powerful person in the world - Trump - in order to borrow some of his status.
It’s to do the opposite of what many of his critics allege is proper; it is deliberately to put Whitehall on warning that it’s Johnson’s way or none.
The point is that there are many Brexiters in the Johnson fan club who see civil servants as the vandals and destroyers of Brexit.
They are viewed as the remainy enemy within, who captured Theresa May and shoved her off the true path to the sunny uplands outside the EU.
So Darroch’s perceived attack on Johnson’s Brexity friend in the White House is paradoxically useful to Johnson.
It gives him a way of signalling to senior mandarins that if they show anything but Stakhanovite commitment to extracting Britain from the EU they can expect early retirement at best or transfer to the salt mines of the departments of transport or work and pensions at worst.
For Brexiters these are necessary desperate measures for desperate times. What Johnson cannot know is whether they will make Sir Humphrey compliant poodle or destructive Poujadist.
And then there is a glimpse through the miasma at the outline of a geopolitical strategy - the Trumpian pact.
Johnson has just one truly warm and significant relationship with a foreign head of state.
And this summer Johnson wants Trump to publicly celebrate his very special relationship with a Johnsonian Britain - in the twin hopes that this expedites a post-Brexit trade deal with the US and (perhaps more important) it persuades EU leaders to belatedly agree an acceptable Brexit compromise, to stay on the right side of a UK that may seem stronger as Trump’s acolyte.
All this may represent the triumph of hope over a clear-eyed view of the US president’s legendary caprice.
But as PM Johnson would begin with a dangerous deficit of goodwill in Paris and Berlin, so he would be clinically bonkers to encourage Trump to shapeshift from unreliable friend into his other diplomatic mode of choice, namely relentless and remorseless enemy.