“Can you go back to your seat please?” asked Andrew Tyrie, chair of the Treasury select committee as Dominic Cummings hovered menacingly over his shoulder.

Cummings, Vote Leave’s campaign director, had no intention of going anywhere. Going back to his seat would be a victory for the cesspit of Brussels. Instead he stood over Tyrie, pointing at his phone.

“I’ve got another meeting at four, so I’ll have to be out of here before that,” Cummings insisted, sticking it to the Man.

“I don’t think you’ve got the hang of these proceedings,” Tyrie replied evenly. “We ask the questions and you stay and answer them.”

“I’m just telling you when I’ll be leaving.”

“In that case you’ll be recalled.”

“Fine by me.”

Cummings sloped slowly back to the other side of the committee room and stood beside his chair.

“Will you sit down, please?” Tyrie persisted.

“I’m just turning off my phone,” Cummings said petulantly. “You wouldn’t want my phone to go off, would you?”

Only when Cummings was certain he had got the backs up of everyone in the room, did he eventually slump into his seat like a moody adolescent. Cummings had a reputation to maintain. He hadn’t yet found anyone he couldn’t pick a fight with – any mirror would do – and he didn’t intend to start now.

“Can we talk about some of Vote Leave’s figures?” said Tyrie, once Cummings was finally in place.

As it happened, we couldn’t. We could talk about why the EU was the most corrupt organisation on Earth, we could talk about why Boris Johnson and Michael Gove weren’t actually members of the establishment, we could talk about why everyone in the Treasury and the Bank of England were complete morons, we could talk about all sort of secret threats that secret people were making about secret things that he would have to keep secret, but talking figures wasn’t on the table.

“I don’t think it’s Vote Leave’s job to provide figures,” Cummings announced triumphantly, his eyes swivelling manically.

“But Vote Leave quotes numerous figures on its website,” said Tyrie, “Most of them misleading or inaccurate.”

“Accuracy is for snake-oil pussies,” Cummings hissed under his breath. “And besides, I’ve got a really bad memory.”

“Is it not true that you only provide the costs of the EU and none of the benefits? You make the same mistake as Boris Johnson. You don’t read carefully enough. Wouldn’t it have been useful to have done some of the maths.”

“It’s just a matter of a few decimal points,” Cummings said.

Tyrie blinked. Earlier on he had been prepared to accept he might have been dealing with an idiot savant. It only now dawned on him that he was just dealing with an idiot complete.

“There are quite a lot of decimal points between £33bn and £16bn,” he pointed out.

“When you’re sitting in your slippers chatting to Mrs Tyrie...” Cummings diverged, worried that he had not yet been sufficiently offensive.

At this point several members of the committee started wondering if there was a doctor on call nearby, but Cummings was only just warming up. No, he couldn’t confirm whether a Vote Leave advert had been deliberately designed to look like an NHS brochure. No, he couldn’t confirm Britain was in the single market, because we definitely weren’t even though we definitely were. No he couldn’t confirm why Vote Leave was claiming that intra EU trade had fallen since 1999 when official figures showed it had actually gone up by 39%.

So it went on. No, he couldn’t confirm when Vote Leave would make the macro-economic case for Brexit because these figures were obviously top secret and if he were to make them public then they wouldn’t be secret any more. No, he couldn’t name the Goldman Sachs operatives who had bribed everyone in Brussels, because he’d be killed. No, he couldn’t name any of of the umpteen ambassadors who had told him at secret trysts that they really hated the EU because if he did they would all just say he was crazy.

“You’re not wrong there,” Labour’s Rachel Reeves observed drily, before leaving to lie down in dark corner.

“For someone who claims to want to give sovereignty back to the British parliament you don’t seem to have much respect for the sovereignty of this committee,” Labour’s Helen Goodman pointed out.

“I want my own special sovereignty,” Cummings shrugged, his look of slight sheepishness suggesting there might be a smidgeon of rationality lurking somewhere in his brain.

The two Tory pro-Brexit MPs, Jacob Rees-Moog and Steve Baker, looked on embarrassed. One appearance by Cummings would have done more for the Remain cause than any number of speeches from David Cameron. They did their best to tee their man up with a few easy questions, much like members of a parole board trying to find some good in a prisoner who has managed for the first time to get through an entire group therapy session without assaulting anyone, but Cummings was much too far gone.