The prime minister takes his game of Brexit bluff to Dublin tomorrow, seemingly unconcerned that his mendacity is now visible to all

The self-image of the public-school ethos from which Boris Johnson springs is best expressed in Thomas Hughes’s high-Victorian novel, Tom Brown’s School Days. But Johnson’s own model is surely not the honourable Tom but the contemptible cad Harry Flashman, as he is so hilariously reimagined in George MacDonald Fraser’s The Flashman Papers. The arch-bounder was sometimes suggested as an avatar for David Cameron but he is surely a better match for Johnson. He rises inexorably to become Sir Harry Flashman VC and brazenly informs us that “all my fame and glory has been earned by accident, false pretence, cowardice, doing the dirty, and blind luck”. Flashman makes his career in the military and explains: “Some human faults are military virtues, like stupidity, and arrogance, and narrow-mindedness.”

We may take assurance from the very fact that Johnson is prime minister that the same goes for politics. Some human faults – mendacity, cynicism, opportunism, bluster, recklessness – are political virtues. But only up to a point. Those qualities have taken Johnson to the pinnacle of power. Shamelessness is practically a requirement for high office. But as we have seen in a dramatic week, the vices that allow you to take power are not much use when you have to wield it – at least not yet and not in a country whose battered democracy retains some life.