The mild-mannered Jo Johnson is an improbable prophet of doom. When he walked out of the Government, declaring Theresa May’s likely Brexit deal ‘a terrible mistake’, he had no inkling of what the coming weeks would bring. With the Conservative Party in turmoil and the Prime Minister facing oblivion, Johnson’s prediction that Britain is facing a crisis comparable to Suez does not sound like hyperbole.

Did he foresee the exodus of former colleagues as appalled as he is by the May deal? ‘No, absolutely not. But I’m glad I did what I did. It was transparently obvious that we would be trapped in a vassal relationship [with the EU].’ Unlike Brexiteers, his brother Boris included, he is crusading for a second referendum that suddenly looks more likely.

‘I shall not cease from mental fight,’ he says. ‘Nor shall my sword sleep in my hand.’ Till we have built Jerusalem? ‘Yeah, in the words of the great William Blake.’ If there is a note of self-mockery in his resolve, that is not surprising. Johnson, as unassuming as his older brother is flamboyant, is not an obvious architect of the promised land. Nor does Orpington, his leafy Greater London constituency, much resemble Jerusalem.