Then they came for the civil service – and all that was left was the blind optimism of the Brexit ideologues

Sir Kim Darroch, the British ambassador to the US, is now in their sights after his unvarnished views on Donald Trump were leaked

No one who was not involved in the process knows how the British ambassador to the United States’ confidential and critical memos about Donald Trump came to be in the hands of the Brexit Party’s in-house journalist, Isabel Oakeshott.

Without such knowledge, all anyone can do is speculate on the motivations and machinations behind the deliberate humiliation of one of the UK’s most senior and most respected civil servants, Sir Kim Darroch, for the crime of doing his job.

The most plausible, and thus the most repeated explanation, is that a Brexiteer with a high-ranking position within government, or a special adviser similarly inclined, has leaked the information to undermine both Sir Kim, an ardent Remainer, and perhaps to prevent Sir Mark Sedwill, the current cabinet secretary and most senior civil servant in the country, from replacing him.

That Ms Oakeshott saw fit to publish the story, and not leave the papers hidden in her attic for several years, as she did with other files that linked Farage funder-in-chief Arron Banks and his associate Andy Wigmore to Russia, makes this explanation more likely.

Theresa May has said she will not sack Sir Kim. How could she? Writing memos to London, giving his views on relations with the White House and its current occupant, is what he is in Washington to do.

Leaks are not uncommon, even major ones like this. But traditionally, they are done by Whitehall officials, or party rivals, to damage politicians. Rarely, if ever before, are they done with the express intention of damaging the civil service.

The Brexit fire is out of control. It is coming for reason, and it is coming for the truth. It is two and a half years since the UK’s ambassador to the European Union, Sir Ivan Rogers, resigned. When he did so, he told his Whitehall colleagues they must carry on having the courage to tell politicians the truth, even if it is a truth they do not wish to hear. Sir Ivan was, and is, the country’s leading expert on the internal politics of the European Union. Theresa May and her associates decided they did not need his advice.

Olly Robbins, the civil servant whom Theresa May appointed to lead her Brexit team inside No 10, has for several years done his civil service job amid outrageous attacks from the more rabidly pro-Brexit press, encouraged by Nigel Farage, Leave.EU and all the rest of the Eurosceptic faction that Vote Leave chief Dominic Cummings once referred to as “the flying monkeys”.

Robbins is now departing for the private sector.

High court judges with the temerity to interpret the law on whether parliament must be consulted before the triggering of Article 50 were labelled “enemies of the people” by the Daily Mail.

And now, the ambassador to the United States and the head of the civil service appear to be the next in line.

On the Today programme on Monday morning, the disgraced former former defence secretary Sir Michael Fallon (not to be confused with Gavin Williamson, the disgraced former defence secretary, or Liam Fox, the disgraced former former former former defence secretary), breezily announced that “all we need is optimism, ambition and energy” to sort out Brexit.

There is a reason this absurd sentiment has not gone away in three long years. It is because optimism is all Brexiteers have left. There is still no plan, still no way to turn an emotional appeal of independence and self-government into a practical reality. Certainly, there is no plan for how to do this without detonating living standards.

And so those with the actual knowledge, those with the responsibility to engage with reality must be swept aside, one after the other, to be replaced by true believers.

Brexit psychosis has now delivered us to a place where 38 per cent of the country, if polls are to be believed, actively want a no-deal Brexit. It is their desired outcome. All warnings of its potential disastrous consequences are dismissed as Project Fear. They do not, in short, believe.

There will, at some point, have to come a reckoning. At the current rate of attrition, the Brexiteers will have left nobody in place to blame but themselves.