Back in November 2002, David Davis spoke in the House of Commons about why he didn’t think referendums were necessarily a good idea. “We should not ask people to vote on a blank sheet of paper and tell them to trust us to fill in the details,” he warned. With good reason. Because the person the country might be relying on for that information could be him.

Detail and Davis are barely on nodding terms. Partly because leaving the EU is a great deal more complicated than he expected, but mainly because he’s hopelessly out of his depth. Davis has yet to be asked any question, no matter how straightforward, that doesn’t take him completely by surprise.

The Brexit secretary has also yet to attend a meeting for which he is fully prepared. At the start of his latest outing to update the Brexit select committee on his lack of progress, Davis spent the best part of 10 minutes explaining why he had to get away early as he had another meeting scheduled that he was already late for. As this was precisely the same excuse he had used at his last appearance, everyone on the committee was underwhelmed.

“I’m very busy,” Davis explained. Busy being busy with busy things. And always at least one meeting behind himself.

As it turned out, the committee had more than enough time to explore the depths of Davis’s knowledge. Largely because he knows so little. On almost every question the Brexit secretary’s stock answer is one of definite vagueness. A man with the utmost confidence in his own limitations.

Hilary Benn, chair of the exiting the European union committee, began by asking how, having spent the past 22 months achieving next to nothing, the government could be sure of reaching an agreement on Ireland in the next couple of months. Because he could, Davis insisted. And if he couldn’t then something would probably be sorted out later.

So it went on. There might or might not be a deal. Parliament might or might not be able to ask the government to renegotiate with the EU. He was making tremendous progress but was unable to list any achievements. He didn’t know if there would be time for the Office for Budget Responsibility to calculate the economic impacts of any deal but it didn’t matter anyway because he would be providing his own assessments, which might or might not exist.

Normally, the Brexit enthusiasts on the committee can be relied on to come to Davis’s rescue by asking him simple questions and congratulating him profusely for his failure to answer. But even they are now beginning to look worried that his air of stupidity may not be an act.

When Davis declared that the real benefit of leaving the customs union was “releasing Liam to sign trade deals”, several members ran out of the room sobbing. When the country’s future depends on Liam Fox, even the Brexiters know we’re screwed.

The only upside for Davis was that he was too dim to realise just what a poor impression he had made.

At prime minister’s questions, later in the morning, Theresa May had no such relief. Her tragedy is that she is self-aware enough to realise she’s not very good, but not so much that she can do anything about it. A kinder party than the Tories would put her out of her misery.

With Jeremy Corbyn, practice may not make perfect but it does make him less mediocre. For the second week running he went in on Windrush and this time he made no mistake. May could only mumble in a dissociated trance. It wasn’t her fault. It was Labour’s. She was going to give people the citizenship rights they already had. It wasn’t her fault ...

“Maybot,” shouted Emily Thornberry. May smiled wanly. Her self esteem is now so low she regards “Maybot” as a term of endearment.

The prime minister ploughed on. She had only wanted to deport a few illegal immigrants. The Windrush generation had just been unfortunate collateral damage. No biggy. It was being sorted and everyone should stop making such a fuss. Tone deaf, tin ear.

It was Yvette Cooper who delivered the coup de grâce. May should stop hiding behind Labour, the cabinet and civil servants. The buck stopped with her. It was her hostile environment policy that had caused the scandal. End of.

“The government isn’t bereft of ideas,” May stammered, her eyes wide in desperation. The situation was far worse than that. Ideas were only the tip of the iceberg. Sans eyes, sans teeth, sans everything.