That David Davis has, for some weeks, been blustering over the non-existence of detailed sectoral assessments of the economic risks of Brexit by saying they might in fact exist, has drawn comparisons in some quarters to Schrodinger’s cat.

David Davis’s simultaneous claims that the work has both been done and not done has prompted a number of over-educated wags to imagine these assessments as existing in a simultaneous state of done and not done.

But that’s not quite right.

If, in his famous thought experiment Erwin Schrodinger had decided he couldn’t be arsed to feed his cat for more than year, then upon its certain death put the lifeless corpse in a box and gone around shouting “IT’S NOT DEAD IT’S NOT DEAD YOU CAN’T PROVE ANYTHING” then you’d be halfway there.

No, this is not some great epistemological conundrum. It is a bullshitter and a blagger trying and pyrotechnically failing to cover its arse.

Finally, on Wednesday morning, David Davis was forced to open the box, the stench of dead cat already hanging heavy in the air, and reveal without even an ounce of ambiguity that – guess what – the cat’s dead.

He even brought a box with him, to the Brexit Select Committee, that is. Two lever arch files, themselves not large enough to contain much more than a dead cat. In fact, we learned, they contained the totality of his department’s assessments on the impact of Brexit on the UK economy, broken down across dozens of different sectors. In size, if nothing else, it bore every outward resemblance not to a comprehensive analysis of how this seismic decision will affect the country, but to a primary-school project on trains.

“Do the impact assessments exist?” he was asked. Davis sucked on a cough sweet and removed and replaced his glasses with such frequency he could still be marketed as a novelty Chinese lucky-cat toy in good time for Christmas.

“There is a formal definition of impact assessments,” he began, his words instantly and inescapably caught in the centrifugal force of the plughole of “no”.

Had he, the Committee Chair Hilary Benn asked him, produced an impact assessment on, say, the automotive sector?

“No.”

“The aerospace industry?”

“No.”

“The financial services sector?”

“I think the answer to all of these is going to be no,” he said.

Brexit: the deciders Show all 8 1 /8 Brexit: the deciders Brexit: the deciders European Union's chief Brexit negotiator, Michel Barnier Getty Brexit: the deciders French President Emmanuel Macron Getty Brexit: the deciders German Chancellor Angela Merkel Reuters Brexit: the deciders Commission President Jean-Claude Juncker EPA Brexit: the deciders The European Parliament's chief Brexit negotiator Guy Verhofstadt Getty Brexit: the deciders Britain's Prime Minister Theresa May Getty Images Brexit: the deciders Britain's Chancellor of the Exchequer, Philip Hammond PA Brexit: the deciders After the first and second appointed Brexit secretaries resigned (David Davis and Dominic Raab respectively), Stephen Barclay is currently heading up the position PA

On previous occasions, David Davis has claimed his department has been analysing the effects of Brexit in “excruciating detail”. That that excruciating detail appeared to be contained in two ring-binders which he did not deny had been produced in the last three weeks, after a House of Commons vote compelled him to publish it.

What his department had been doing was apparently “sectoral analyses” not impact assessments. There was, apparently, no point in actually forecasting the risks of Brexit. David Davis was, he said, “not a fan of economic models because they’re always wrong”.

Brexit would be a “paradigm shift” and yes, at this point, its most fervent cheerleader and now chief negotiator did liken it to the “financial crash of 2008”.

There would be no point in seeking to predict the economic impact of Brexit, because “no one saw the financial crash coming”.

No, they did not. But if you’d told JPMorgan, Goldman Sachs and the rest of them that the financial crash was coming, and not merely that but you were able to tell them the precise date more than two years in advance, it’s fair to imagine they would not have said: “Well, there’s not much point in planning for it. We’ll see how it goes.”

It doesn’t matter much, this, in the grand scheme of things. That the nation is hopelessly underprepared for Brexit and that David Davis is utterly clueless is common knowledge to anyone even vaguely intimated with the process.

In one of his final public utterances before deleting his Twitter account, the former Vote Leave director Dominic Cummings memorably described Davis as “thick as mince, vain as narcissus and lazy as a toad”.