Kim Darroch, the British ambassador to the United States, resigned after his confidential blunt assessment of President Trump was made public. (Erin Schaff for The Washington Post)
Matt Potter, a British journalist and broadcaster, is the author of "Outlaws Inc.: Flying With the World's Most Dangerous Smugglers" and "The Last Goodbye: A History of the World in Resignation Letters."

It was a cultural Defcon 1, enough to make the British break out in a sweat, or at least deploy the emergency stiff upper lip, the one reserved for the trickiest of pickles. Brexit, for once, was not the issue, but rather leaked diplomatic cables that had exposed the wholly blunt assessment of President Trump by the British ambassador to the United States, Sir Kim Darroch.

To be clear, it wasn’t so much the assessment, or indeed the response of a wrathful president (“We’re not big fans of that man”), that made the British shiver as we knocked back a steadying cup of tea. It wasn’t even the whispers that the leak was a maneuver by Brexiteers to have Nigel Farage — Brexit’s very own flatterer in chief to this uniquely fragile and praise-hungry POTUS — installed in Darroch’s place, as dark a prospect as that is.

This sudden chill ran deeper. It tapped into something existential. About our worst fears as a nation. About who we are. If being British means anything, it is surely our ability to speak perfectly clearly and with absolute candor while still managing to be bafflingly, frustratingly elusive as to what we really mean.

This trait forms the foundation on which Brand Britain is built. It’s behind the appeal of our movie stars — from Hugh Grant’s tongue-tied leading men to every one of Hollywood’s sardonic, supercilious supervillains. It’s there in the distancing personae and gnomic uncanniness of our pop; in David Bowie and Radiohead. It’s there in the way we offer our highest praise (“not bad at all”) and our most scathing critiques (“interesting”), our manners, our social and gender roles, our consumption habits. One of the great pleasures for Brits in watching American TV — sports, drama, movies, news, you name it — is gape-mouthed boggling at just how often people confront one another. Like, openly. It turns everything — earnest family healing moments, tough-guy talk, interviews — into brilliantly addictive comedy-horror. (Netflix, you’re missing a category over here.)

And yet. One of our most senior diplomats chose to drop the double-talk, to trust his listener, to abandon one of our most sacred national characteristics. Darroch used words such as “clumsy,” “inept” and “uniquely dysfunctional” to describe the administration, writing that Trump “radiates insecurity.” For Britons, this kind of unvarnished talk is more than an inexplicable error: It is an aberration. Something akin to an experienced mountaineer stripping to the waist and walking off into a snowstorm, a desert traveler running for the mirage in the sand. We look on, aghast, and shield our young. He let it slip. He sealed his fate.

But why? And how might he have survived?

He could have followed the classic rule of the British workplace. It’s a rule that’s been made very clear to me on at least 12 occasions in my own short career. (No, no, never explicitly; don’t be a fool. These were offices in Britain, so of course I read between the lines to discern what my bosses actually meant.) Never, ever, commit anything to writing that you would not feel entirely comfortable with if it fell into the hands of your sworn enemy. And yet you must also say what you need to say. So you speak in a way that leaves room for charity, for even the smallest degree of uncertainty. Do we disagree? Are we at loggerheads? Possibly. Even probably. But there must always be an appeal to that most British of graces, the benefit of the doubt. Let positive and negative interpretations hover in a kind of quantum superposition. Schrödinger’s email. The message was written, and read, and even understood; but who can be 100 percent certain what it contained?

This is not shadowboxing for the sake of it, less still slipperiness or dishonesty; in fact, Brits see it as a service. It has the effect of encouraging the reader to react with a measure of caution, lest they have it all wrong. It helps them avoid an awkward scene — the very thought — and helps us all avoid binary judgment. Hey, presto: We understand one another perfectly, yet have fewer damaging fallouts. It helps us all get along.

This is not a recent development.

From Sir Walter Raleigh and the Tudor courtiers of the 16th century to the metaphysical poets of the English Civil War, whole periods of Britain’s cultural history have been shaped by the need to clothe our messages, to make them plausibly deniable. To write in a kind of vanishing ink, lest the manuscript fall into the wrong hands and condemn the writer to the Bloody Tower or the noose. “Alice in Wonderland” author and amateur cryptographer Lewis Carroll wrote stories and poetry that drip with critiques of Victorian mores and governance, disguised as fantastical children’s nonsense verse, inscrutable riddles and shaggy-dog stories. In the words of Shakespeare’s wise Fool to the raging, vain, bullying, needy and mentally weak King Lear: “Have more than thou showest/ Speak less than thou knowest.” Of course, when the bloodbath commences, the Fool simply vanishes. As Lear’s inner circle and entourage snuff it gorily, he is nowhere to be found — just a lingering puff of rumor and unreliable reports. One can’t help feeling he is the smartest diplomat of the lot.

British government business is successfully navigated through drive-by riddling to this day. Postwar prime minister Clement Attlee was said in a newspaper column by an unnamed opponent — commonly supposed to have been Winston Churchill — to be “a modest man, with much to be modest about.” A judgment cloaked in terms Trump might not have seen through. For all of Boris Johnson’s moral and intellectual faults and disqualifiers for high office, this is perhaps his chief skill. He speaks in a way that is both a joke and serious. Asked recently what he does to relax, he declared, to much derision, that he enjoys crafting and painting model vehicles — buses, mainly. A day later, Guardian journalist Carole Cadwalladr realized it appeared to be a covert reference to the bus in which his Brexit campaign had toured the country in 2016, with controversial and misleading figures about the benefits of leaving the European Union painted on the side. He had apparently told the hobby anecdote to knock references to that campaign bus off the top of his Internet-search results.

No wonder “what British people say vs. what they really mean” is a subject that surfaces regularly; in books, in news, in culture, around the world. This is a land where “Please, it was entirely my fault — don’t give it another thought” means “It was your fault, I am furious, and you are now dead to me.” Where “Interesting idea — please think about that some more” means “That’s a bad idea; don’t do it.” And where “Yes, I’ll probably join you at the pub later on” means “I am not leaving my house tonight unless it’s on fire.”

We are, in the end, prisoners of geography. On such a small group of islands, you have to get along. Make do. It’s one thing for alienated American teens and fugitives to run away to California or New Mexico; for beat poets to ride railroads; for bums to hit the endless highway, to break for the border. It’s quite another to know you’re never more than 70 miles from one edge or another of your little island. So you do what sailors on ships or bands on tour do in cramped conditions. You appear to get along famously while learning how to make yourself clear, buy yourself space, stay sane and subtly mess with as many heads as necessary to get by. It’s no coincidence that Brits feel a sort of secret understanding on this front with Japan — another small island nation with a similar thing about manners, nonconfrontation, indirect expression. “Passive-aggressive” — an American military term, no less — is such a blunt term for what, really, is an art.

It’s also an article of faith in British diplomatic life. The age-old fear in diplomatic circles is that one of your own will adopt a host culture; that an envoy will end up loving the alien, to coin a Bowie lyric. But these are times when getting too cozy among old allies and friends can be outright dangerous. Darroch, like every ambassador, had the right to expect that the confidential nature of his briefings to his superiors at the Foreign Office and Downing Street would be respected. Yet one of the leaked cables concludes, “You need to make your points simple, even blunt,” to be understood by Trump. One cannot help wondering if it had become a habit. What Darroch wrote may have been correct, but he was speaking American.

Our collective shudder is not just for the ambassador, who was forced to resign, or for the partisan times in both our countries that led to his ouster. It is for the perilous and clearly insane idea of speaking in a way that wasn’t open to some misunderstanding. That was Darroch’s downfall.