During his appearance at the official inquiry into the pandemic on Wednesday, four people were removed from the public gallery after holding up pictures, along with the words: "The dead can't hear your apologies."

Mr Johnson told the hearing he was "deeply sorry for the pain and loss and suffering".

But he said he hoped the probe would be able to "get answers to those very difficult questions" that victims and their families were "rightly asking".

Boris Johnson COVID evidence - as it happened

During the evidence session, that will continue on Thursday, the inquiry heard varied testimony from the former prime minister, including:

• The government "underestimated the scale and pace of challenge" from COVID - thinking the peak would come in May or June;

• The tone of private WhatsApp exchanges was a "reflection of the agony" the country was going through;

• A denial he was on holiday over the half-term break in February 2020 - as claimed by former aide Dominic Cummings

• Mr Johnson explaining that he "can't say" whether he would have "gone earlier" in ordering the first lockdown, but that he took "full responsibility" for the decisions made;

• The former prime minister offering an apology to sufferers of long COVID, having described the condition as "b*****ks" in 2021;

• He stood by Matt Hancock, saying the then health secretary did "a good job" whatever his "defects".

Read more:
Whatever Boris Johnson said, the evidence pointed to leadership failures
Key points from Boris Johnson's evidence

Speaking on his first day of questioning at the COVID inquiry he set up to learn the lessons of the pandemic, Mr Johnson said "unquestionably" mistakes were made by his government, adding that he took "responsibility for all the decisions that we made".

Within that included the lockdown decisions and their timeliness, the circulation of the virus in the residential care sector, and the Eat Out to Help Out scheme.

The ex-prime minister, who was ousted from Downing Street in the summer of 2022, said he acknowledged that "so many people suffered, so many people lost their lives".

But he said the government was "doing our best at the time, given what we knew, given the information I had available to me at the time, I think we did our level best".

Mr Johnson placed some blame on the different messaging coming from the different governments in the devolved nations of the UK.

"There was far, far more that united us than divided us," he said. "[But] understandably they're looking to talk directly to their own electorates, there were going to be times when they differed from the main UK government message.

"And I thought that was sometimes at risk of being confusing at a time when we really needed to land messages simply."

But Hugo Keith KC, who led the questioning for the inquiry, asked Mr Johnson why he did not foresee the scale of destruction the COVID pandemic would cause in early 2020, given that the inquiry had seen evidence to suggest others in Westminster were concerned as early as February.

Mr Johnson admitted the wider government "underestimated" the threat posed by the virus, saying the "concept of a pandemic did not imply to the Whitehall mind the kind of utter disaster that COVID was to become".

He said in the "early days of March", government figures and officials "were all collectively underestimating how fast it had already spread in the UK" and thought the peak would be in May or June which turned out to be "totally wrong".

"I don't blame the scientists for that at all," he said.

"That was the feeling and it just turned out to be wrong."

Long COVID

Mr Johnson was also questioned about his remarks over long COVID - a condition which, according to Oxford University, affected up to 10% of people who caught the virus.

Documents shown to the inquiry had scribbles alongside by the prime minister, referring to it as "b*****ks" and "Gulf War Syndrome stuff".

Mr Johnson said he realised the remarks had "caused hurt and offence", adding: "I regret very much using that language and should have thought about the possibility of future publication".

But he claimed he was trying to "get to the truth of the matter" and to get officials "to explain to me exactly what the syndrome was".

Hancock criticism

A running theme of the inquiry has been criticism of the then-health secretary Mr Hancock, with former advisers and civil servants having revealed they called for Mr Johnson to fire him for his performance during the pandemic.

But when asked about these calls for Mr Hancock to go, the former prime minister appeared to stand by his decision to keep the secretary of state in post.

He said he was "aware" that the Department of Health and Social Care (DHSC) was "under fire from loads of people", but added: "The point is you have got a lot of very talented, sometimes super-confident, sometimes egotistical people, who are crushed with anxiety about what is happening to their country, who are wracked secretly with self-doubt and self-criticism, and who externalise that by criticising others and it is human nature.

"When you are the leader in those circumstances, your job is to work out what is justified and what is people sounding off, and what is political nonsense, and my judgement was that Matt was, on the whole, doing a good job in very difficult circumstances and there was no advantage in moving him as I was being urged to do."

Pushed again on the other calls for him to go and reports of "chaos" in the DHSC, Mr Johnson said he thought his health secretary was "intellectually able" and "top of the subject", adding: "Whatever his failings may or may not have been, I didn't see any advantage to the country at a critical time… in moving him in exchange for someone else when I couldn't be sure that we were necessary going to be trading up."

Missing WhatsApps

In the days leading up the inquiry there were reports anticipating Mr Johnson's apology and the fact that not all of his WhatsApps would be made available to the inquiry - with about 5,000 messages on his phone from January 30, 2020 to June 2020 missing.

Baroness Hallett, who is chairing the inquiry, raised the issue of people briefing the press ahead of a witnesses' appearance, arguing that a leak "undermines the inquiry's ability to do its job fairly, effectively and independently".

Mr Johnson said he did not know the "exact reason" the messages had not been located, but said it was "something to do with the app going down and then coming up again, but somehow automatically erasing all the things between that date".

"Can I, for the avoidance of doubt, make it absolutely clear I haven't removed any WhatsApps from my phone and I've given you everything that I think you need," he said.

Mr Keith told Mr Johnson that other figures' WhatsApp messages that have previously been shown to the inquiry "paint an appalling picture, not all the time but at times, of incompetence and disarray".

Mr Johnson argued that plenty of successful governments have "challenging and competing characters whose views about each other might not be fit to print but who get a lot done".

Read more:
Gove apologises for pandemic 'errors'
Inquiry about 'scapegoating' senior govt figures

The former prime minister said the tone of the private messages was a "reflection of the agony" the country was going through.

"It was a very difficult, very challenging period," he said. "People were getting - as you can see from the WhatsApps - very frazzled because they were frustrated."

Mr Johnson is the latest in a line of government ministers to have appeared in front of the inquiry, including Mr Hancock, former deputy prime minister Dominic Raab and Levelling Up Secretary Michael Gove, but by far the most anticipated.

He will return to the hearing on Thursday morning to continue to give evidence.