Baffled, punch-drunk Boris Johnson is forced to contemplate a moral universe | John Crace

a Long before the proceedings were due to begin, a large number of men and women from the bereaved had gathered outside the anonymous Covid research building in west London. But not quite early enough. Boris Johnson had sneaked in shortly before 7am. So brave. Always willing to stand behind the decisions he made. Always ready to stand up and be counted. To look his accusers in the eye.

Heather Hallett, the chair of the inquiry, got things moving with a reprimand. Witnesses were not supposed to pave the way by telling the newspapers the details of their defense before their appearance. Johnson looked surprised. He had no idea how much had been leaked to friendly sources. It was completely mind-boggling. There's nothing to do with him. Perhaps these political editors were telepathic. He also had no idea why so many of his allies had written pieces in recent days that trashed the investigation. God moves in mysterious ways.

“I promise to tell the truth…” Johnson said as he took the oath. Was this the first philosophical riddle of the day? Was what we were about to discover at best a partial truth and even an outright lie? Because that is what the convict has always done. He has lied to friends, family, women and the country. He lied in parliament. So why should things be different now? He had no intention of undergoing a personality transplant in the legal context of the investigation.

Does the convict know that he is lying? Is he so disconnected from reality, so locked in his solipsistic narcissism, that he convinces himself that the truth can be whatever he wants – whatever he needs –? The ultimate moral relativist. Where every truth has a half-life, measured in minutes. Or is there a part of Johnson that recognizes what he's doing? That feels compromised and diminished by his actions. Whose every untruth further corrodes what passes for his soul.

We started with the missing WhatsApp messages from the convict. Lead counsel, Hugo Keith, asked what happened to the messages between January and June 2020. Johnson shrugged. He was devastated to discover that he had had the one phone on the entire planet from which it had been impossible to retrieve messages. And he forgot the password. 1234.

It was all the more frustrating because he had received so much fascinating technical training from Jennifer Arcuri. Mostly horizontal. Had he tried to reset the phone to factory settings when he realized that so many messages could be incriminating? Johnson looked bewildered. He and Arcuri hadn't gotten to the factory settings page while pole dancing.

Then the convict muttered an apology. Soz that so many people had died, but he had done his best. That's about it. It didn't sound sincere and sincere. No sense that more could be expected of him as Prime Minister. The relatives did not sound too impressed. As always, Johnson expected forgiveness to be granted without any sense of remorse. What had been his biggest mistake? Simple. I don't coordinate messages between England, Scotland or anywhere else. Wales and Northern Ireland were apparently wherever. YEP. Because that was the big question everyone wanted to ask.

Keith pressed on. Britain had one of the highest death rates in Europe. No, that didn't happen, Johnson said. We were about average. The friendly KC sighed emphatically and brought up a slide showing that Britain was second to last. The convict seemed surprised that a lawyer actually had any evidence.

This was an interruption that would last all day. We're told Johnson spent 10 days preparing his defense with his legal team, yet he was blindsided again and again by the most obvious questions. Those legendary powers of concentration. Or maybe he assumed every lawyer was as rubbish as Suella Braverman.

Within minutes Johnson looked drunk. Sweaty, pale and sly. No matter what he's done in the past year, he hasn't gotten into shape. He then blamed the government for the slow lockdown. He would have done it much sooner. A lie. Keith pointed out to him the evidence of previous witnesses who had said the Cabinet had been sidelined all along. Oh, the convict shrugged his shoulders grumblingly.

Then Keith welcomed Johnson to a whole new world. That of life in Number 10. Boris had no idea Dominic Cummings was a potty-mouthed sociopath. This is a shock. He also had no idea that Downing Street was completely dysfunctional. Chaos had always followed him wherever he went, so it was completely normal for him to have everyone hating each other while he was getting angry and fucking against the copier. He was sure that Margaret Thatcher regularly called Nigel Lawson a 'useless bastard'.

It had now become clear that Johnson had rarely been aware that he was meant to be Prime Minister. He seemed genuinely surprised when Keith told him. There too, his memory loss was almost total. He could remember almost nothing of the first months of the pandemic. Like Party Marty, he believed that if you could remember your time in Downing Street, you weren't really there. It wasn't his job to pay attention.

The more detailed the questions became after lunch, the more confused Boris became. It had been a long day and he was now used to dozing around. He was sure that he had done mostly the right things and it was harsh to criticize. No one could have expected Covid to creep in while he was celebrating Brexit and on a ten day break in Chevening. Cobra was for cissies. And if you exclude all the things he hadn't done – almost everything – he had done just about everything that could be expected of a man who struggled to take responsibility.

With a returning sense of conscience, Keith kept returning to a sense of right and wrong. Johnson was baffled by this leitmotif. Understandable. He is not familiar with a moral universe. The only thing that ever mattered was his self-preservation. In retrospect it was a strange country. A place where he can be expected to be capable of self-reflection. When he talked about letting people die, it was only as a rhetorical device. No one could have done more for the country than him. To call him indecisive was slander. Often he made a decision. It's just that he was in the habit of changing it then.

Around half past five Hallett put Boris out of his misery. It had been a long day. Tomorrow it might take longer. Johnson continued to argue that no one could have done it better. That his government was a beacon of common sense. Few of us can remember being agape at the incompetence at the time. Three and a half years later, we are still open-mouthed.

• John Crace's book Depraved New World (Guardian Faber, £16.99) is available now. To support The Guardian and Observer, order your copy and save 18% on Guardianbookshop.com. Delivery charges may apply.