Let’s start by revisiting Boris Johnson’s interview with Deutsche Welle last month, on whether the poison used in the Salisbury attack came from Russia:

Boris Johnson: Let me be clear with you … When I look at the evidence, I mean the people from Porton Down, the laboratory …

Deutsche Welle: So they have the samples …

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Boris Johnson: They do. And they were absolutely categorical and I asked the guy myself, I said, “Are you sure?” And he said there’s no doubt.

Well, that’s odd. I could have sworn Gary Aitkenhead of Porton Down told Sky News that the “precise source” of the poison could not be identified. One of these men is wrong. Could it be the scientist who deals in cold hard evidence for a living, or Britain’s Donald Trump: complete with ludicrous hair, incomprehensible oratory and a casual relationship with the facts?

A functional British press would have investigated whether our foreign secretary may have lied to the world about the activities of another country, but alas the media’s leading lights were too busy implying Jeremy Corbyn’s attempts at urging caution were evidence of some kind of fervent lack of patriotism.

I can only paraphrase Clement Attlee: 'a period of self-reflection on your part would be most welcome'

Here we have two responses to foreign policy: one is based on the careful examination of the evidence and employing diplomacy, the other involves rushing headlong into a conflict with a heavily armed superpower. The foreign secretary has opted for the second option, being careless with the facts in order to achieve it. The first – the one we can now perhaps agree is preferable – was derided by much of the media, the Tories, and Labour’s self-styled moderates as being disunited and unserious. Most of these people also transformed into armchair generals as soon as the Iraq war was mooted, an act that predictably became Britain’s biggest foreign policy disaster of the last 30 years. In response to them, I can only paraphrase Clement Attlee: “a period of self-reflection on your part would be most welcome”.

Inevitably, Russia has clutched its national pearls over the comments from Porton Down and accusations of such a heinous act, and tensions with Britain have escalated. And yet Boris Johnson, who was gleefully stoking the fire just two weeks ago, remains in post. Surely one of the most basic requirements of being foreign secretary is not lying on the international stage and deteriorating relations with other countries?

There are numerous possible reasons for Johnson’s Teflon-like qualities. Perhaps the privilege of rich white men really is so pervasive that they can literally do whatever they feel like and not suffer any consequences. Perhaps the reason it’s so hard to shame Johnson is that he appears to lack the capacity to feel shame. Or, perhaps the hostage situation our prime minister has found herself in since the last election means that she can’t tell Johnson to Foxtrot Oscar, no matter how badly he behaves. In any case, a straw must surely break the camel’s back – and it may as well be this. If lying to the country about something so serious doesn’t return Johnson to the back benches, what will it take?

• Ellie Mae O’Hagan is a freelance journalist and commentator