If the leak of Sir Kim Darroch’s cables was a pro-Brexit plot to get rid of a non-believer, then it worked a treat.
By refusing to back Sir Kim in Tuesday’s television debate, Mr Johnson (I’m sorry, I don’t subscribe to his more cuddly moniker) disowned a civil servant who had simply been doing his job by pointing out the shortcomings of a new administration.
Theresa May could see that. Jeremy Hunt could see that. Liam Fox could see that. In fact, everyone could see that – apart from Boris Johnson and Nigel Farage, who was calling for the so-called Europhile ambassador’s resignation on the very day the story broke.
So, what does this tell us about what to expect from a Johnson premiership?
Firstly, it shows that our expected new prime minister will happily kow-tow to Donald Trump, who has begun treating Britain like a 51st state – calling our current leader “foolish” and her attempts at Brexit a “mess”.
It’s almost as if, with his buddy about to take over, the US president can’t wait to get stuck in – polarising our country’s politics in the same way he has his own.
And if Sir Kim Darroch is his first test as a would-be prime minister, then Mr Johnson has fallen at the very first hurdle. For, if you don’t stand up for your side, then morale and support can very quickly slip away.
Just as Trump has driven a coach and horses through Washington politics by not playing by the rules, so it appears will Johnson.
But what did we expect? It was for good reason that Mr Duncan was described as Johnson’s “pooper scooper” when our would-be PM was foreign secretary.
The messes he had to clean up after his boss were plentiful enough: Johnson’s most famous gaffe was when he wrongly claimed a British mum jailed in Iran, Nazanin Zaghari-Radcliffe, had been teaching journalists.
He claimed his mistake, which it was claimed had stiffened her captors’ resolve, hadn’t actually made any difference – but try telling that to her husband, Richard.
As foreign secretary, Johnson also recommended the UK allow Saudi Arabia to buy British bomb parts expected to be used on Yemen, just days after an airstrike on a potato factory there killed 14 people.
The day after his email approving the sale, a village school in Sa’ada province was hit by another Saudi airstrike, killing 10 children and injuring 20.
In Mr Duncan’s words, “cleaning up after him was quite a full-time activity”.
Later, after resigning as foreign secretary over the Theresa May’s Chequers plan, Johnson made an all expenses paid trip to Saudi Arabia costing £14,000.
Small wonder then that he did little to call out the Riyadh authorities for their harsh blockade of Qatar, now in its third year, and widely blamed for a rift in the Gulf Cooperation Council which has only served to bolster Iran’s position in the region.
Even the one thing Johnson does take credit for during his stint at the foreign office was not down to him. He described the expulsion of 153 Russians by 28 countries following the Salisbury attacks as ‘the single biggest diplomatic coup this country has pulled off that I can remember’.
But the real mastermind behind the operation was Theresa May’s national security adviser, Mark Sedwill – but then who’s not had a boss happy to bask in the glow of someone else’s good work?
Commentators have noted how during his leadership campaign Johnson has talked much about his work as mayor of London, but hardly his time as foreign secretary.
Could this be because a man born with a silver spoon in his mouth who has busked his way through life is uniquely unsuited to a job where you are buffeted by events on an almost daily basis?
Like being prime minister.
Donald Trump can get away with insulting other countries (he once suggested Montenegro was so aggressive it could start World War Three) because organisations like Nato still rely on the Yankee dollar.
But Johnson won’t be able to do the same – unless we are so aligned with America that we do become that 51st state, shooting from the hip in that brash Trump-like way that Johnson would no doubt call ‘optimistic’.
Is the UK ready for a prime minister who, like Trump has bypassed Congress, prorogues Parliament? We’ve already had Johnson decrying the ‘Brexit Bashing Corporation’, how soon before those who peddle negative stories are the “enemy of the people”?
Boris Johnson has been called a hypocrite because he opposed Gordon Brown becoming prime minister after Tony Blair without a mandate from the British people – something which he appears about to do himself.
When asked about it recently he retorted: “He wasn’t taking over in the context of a national political crisis where we need to get Brexit done”.
Stand by for other ways that ‘a national political crisis’ is used as an excuse for not doing things as one might expect.
Such as not standing by one of your ambassadors when a host country demands his removal – to have him replaced by someone, in the words of an ex-British ambassador to the US, “more congenial”.
Anthony Harwood is a former foreign editor of the Daily Mail and US Editor of the Daily Mirror