Boris Johnson: Did MPs pierce the ex-PM's armour?
Boris Johnson was questioned about events in Downing Street during the Covid lockdown and his subsequent statements to MPs, for around three hours on Wednesday.
But in the marathon session, there were several key moments which cut straight to the heart of the committee's remit to find out whether the former prime minister deliberately misled the House of Commons.
Passing drinks
Asked what mitigations were put in place at No 10 events, Mr Johnson says efforts were made to avoid physical contact, and "we didn't pass stuff to each other if we could possibly avoid it".
Harriet Harman, the Labour chair of the committee, jumped in to point out that the committee has seen photos that show staff passing drinks to each other.
Mr Johnson replied: "This is guidance, and I'm not going to pretend that it was enforced rigidly. But that's explicitly what the guidance provides for."
Mr Johnson has maintained he acted on advice of his trusted officials.
But he now says while he had been assured that the rules had been followed at the December 2020 press office Christmas party (which he didn't attend), he had not been assured about the guidance.
He maintains that when the senor civil servant Martin Reynolds told him "whether it was realistic to argue all guidance had been followed at all times" - which he did subsequently claim in the Commons - Mr Reynolds was simply referring to the difficulty in maintaining "perfect" social distancing in No 10.
Ms Harman may, though, have pierced the Johnson armour when she interjected with a question about behaviour at a November leaving do.
When she said people had been passing drinks to each other, the ex-PM said he was not saying guidance "was enforced rigidly".
So why subsequently tell MPs that guidance had been followed completely and at all times?
What would you have said at a press conference?
Conservative MP Sir Bernard Jenkin also asked Mr Johnson whether he would have said it was OK for organisations to hold "un-socially distanced farewell gatherings in the workplace" during his Covid press conferences.
Mr Johnson said he would have said it was up to organisations "to decide how they are going to implement the guidance, amongst which is social distancing".
He says the guidance allowed them to have mitigations in place where "they can't do social distancing perfectly" - and there were "plenty of mitigations" inside No 10.
Mr Johnson didn't sound at his most confident when he suggested it was up to organisations themselves to interpret social distancing guidelines.
This was an important question, because he had stressed the need for social distancing time and again at press conferences, with podiums emblazoned "Hands. Face. Space".
So the committee wants to establish that it would have been obvious to Mr Johnson that two leaving dos in November 2020 may have been in breach.
And therefore, that he may have known he was misleading the Commons when he said guidance had been followed "completely".
Sir Bernard points out that the guidance didn't say people could have "thank-you parties and invite who you like".
'Slipped my mind'
Labour's Yvonne Fovargue asked Mr Johnson whether he had "reflected" on the June 2020 birthday gathering - which he was fined for attending - before he later told the Commons that Covid rules and guidance had been followed at all times.
Mr Johnson replied: "No I didn't, and that's because it was a long time ago, I'm afraid it had entirely slipped my mind, and I thought it was a completely innocent event. It was a very brief event."
The committee is exploring again whether it was "obvious" to the former prime minister that guidance was being breached because it was attended by his wife, son and - briefly - his interior designer, and that they did not need to be there for work purposes.
Why worry about optics?
When asked about written evidence given by Lee Cain, his former communications director, expressing concerns about a drinks event in the No 10 garden in May 2020, Mr Johnson said Mr Cain had been "concerned about the optics, not about the rules".
Following up, Ms Fovargue then asked: "If the event had been within the rules, why was he concerned about the optics?"
To this, Mr Johnson said he thought Mr Cain was concerned about the "impression that people might gain if they looked over the garden wall and thought that we were doing something that other people weren't allowed to do".
This could be a significant moment. The PM said that the "bring your own booze" gathering in May 2020 was a work event, and reasonably necessary for work purposes.
But in an email, his then-communications chief Lee Cain warned of the "comms risk".
The then-PM told the committee that's because people might have thought they were doing something other people weren't allowed to do.
The committee may suggest that this response demonstrates that the question of whether the event was compliant must have crossed his mind.
Mr Johnson's defence was that the senior civil servant who instigated it, Martin Reynolds, believed it to be within the rules.
This is the event that Dominic Cummings maintains he warned the PM about, but Mr Johnson has described his former top adviser as "discredited".
'You didn't say it at the time'
Mr Johnson described the measures he said were in place to mitigate the risk of Covid in Downing Street, including sanitisers, keeping windows open, holding meetings on Zoom, Perspex screens between desks and limits on the number of people in rooms.
He added that regular testing helped "mitigate the difficulties we had in maintaining perfect social distancing".
In a terse rejoinder, Sir Bernard replied: "I'm bound to say that if you said all that at the time to the House of Commons, we probably wouldn't be sitting here. But you didn't."
This was a crucial point from Sir Bernard.
The committee is examining whether the then-PM misled the Commons, and whether that was inadvertent, reckless or intentional.
Mr Johnson explained why it was difficult to maintain perfect social distancing in Downing Street, but why then did he tell MPs that Covid guidance was followed "completely" and "at all times"?
He had not sought to explain to the Commons the constraints of working in No 10.
Those constraints may have been understandable, but that is not what he said when challenged on breaches of guidance in Parliament.
The rules at the time in question allowed for 1m social distancing, with mitigations.
Mr Johnson suggested mitigations such as screens were in an "adjacent room" - and a leaving do he attended in a vestibule had been "impromptu".
However, Mr Johnson's overarching defence is that he believed he hadn't breached the rules, so demolishing any suggestion that guidance wasn't flouted doesn't in itself prove that he thought he was not telling the truth to MPs.
Name an official
Conservative MP Alberto Costa asked Mr Johnson to name the officials the former prime minister said in his written evidence had given him assurances about events that turned out to be "wrong".
After initially saying he couldn't, Mr Johnson says there is "at least one adviser I can think" of, but they had asked the committee not to be named.
Mr Johnson then agreed to a request from Mr Costa to provide the committee with the answer in writing after the hearing.
But he added he was advised "by different people, on different occasions" that the rules had been followed.
The committee is probing on Mr Johnson's assertion that he got repeated assurances that there was no rule breaches.
If it appears that the PM hadn't sought advice widely, the committee might contend that he was "reckless" in claiming rules and guidance were followed at all times.