Professor Devi Sridhar, who is the chair of Global Public Health at the University of Edinburgh, is the next witness.

She explains many of the questions Britain was grappling with were exactly the same questions as being asked internationally.

The academic says every country has something to learn from other countries and there needs to be a degree of humility when looking at parts of the world that have been hit badly.

"Infectious diseases is not really a high income world problem," she explains.

Prof Sridhar says: "That was very valid that we had to look at other places and learn from them."

She says we had time to learn from other countries and the Covd outbreak on the Princess Diamond cruise ship, which was quarantined in Japan in February 2020

High income countries had not faced anything like this, she says, adding "there was a sense of complacency across high income countries".

Professor Jason Leitch says a reference to lockdown being an old-fashioned way to manage pandemic in an interview he did with the Spectator was "slightly misunderstood".

"When you have a disease that you don't understand, pretty much the only thing you have in the public health tool box is to take infected individuals and separate them from the rest of society," he says.

"I didn't suggest for a moment that it wasn't the right thing to do. Unfortunately because we had no vaccine, no therapeutics, no way of managing it, it was the only thing left."

He adds that there might be further reflection about closing schools so quickly, as everyone did round the world.

Most children were not seriously ill from Covid, but they were also trying to protect staff, families and the broader community, he says.

Image source, Getty Images

Jamie Dawson KC asks if the FACTS acronym was too complicated for the public.

• Face coverings should be worn in enclosed spaces
• Avoid crowded areas
• Clean your hands and surfaces
• Two-metre distancing remains the clear advice
• Self isolate, and book a test immediately, if you have symptoms of Covid-19

Professor Leitch says the idea wasn't for the public to memorise it, it was for things like posters

He does not think it was overly complicated, rather it was a good thing.

Mr Dawson points out only 1% of people could recall all five FACTS and he asks if it could not have done far more simply.

The national clinical director says the icons became used around the country.

Prof Leitch says it was "hugely difficult" to deal with misinformation and he is still attacked on social media.

He says the general advice is not to fight mis-information but "to continue to tell the truth and use the science to compete against that in the public mind and that truth would then win the day."

Misinformation was mostly about vaccination, he says,

Prof Leitch adds it started at the beginning of the pandemic when theories emerged that the global health crisis was not as serious as people were being told.

He says the government was candid about what was happening in Scotland and the first person who died in Scotland.

Responding to Jamie Dawson's question that person died from Covid after attending the Scotland rugby match in France on 8 March, he says he was not aware of that.

Jamie Dawson KC turns to messages between Prof Leitch and Kate Forbes, who was the finance secretary at the time.

Ms Forbes was seeking advice on her first podium appearance.

Prof Leitch says he was "relatively flippant" when he said the press conferences were not well organised.

There was switching around at short notice of who would appear before the media, he says.

But the national clinical director insists the data for the press conferences was "very well organised".

Image source, Getty Images

Jamie Dawson KC asks about criticism that the then First Minister Nicola Sturgeon used the daily media briefings for political gain.

He asks if this was considered in the media strategy as something that might undermine their important message.

"It wasn't considered in my hearing or in my view at any time," Prof Leitch says.

"There was never a suggestion it should be done in a political way or should follow a political course."

He adds that it was "categorically untrue" that he was giving advice "based on political difference".

Jamie Dawson KC returns to the WhatsApp messages and brings up message from Ken Thomson - former manager of the Covid Co-ordination Directorate of the Scottish government - which warns the topic is "discoverable under FOI".

Mr Thomson goes on to says "plausible deniability are my middle names. Now clear it again."

Mr Dawson asks if this does not show a senior civil servant telling you that you should delete messages which are discoverable under FOI.

Prof Leitch says that's a matter for Mr Thomson and he says the FOI rules are not as simple as hold onto every record

"My position remains that I followed the guidance at all times, including and bearing in mind what that guidance said about FOI rules."

Analysis: Messages revealing in their franknesspublished at 11:45 Greenwich Mean Time 23 January

11:45 GMT 23 January

Kirsten Campbell
BBC Scotland political correspondent

We've seen our first informal messages from the former First Minister Nicola Sturgeon and the current First Minister Humza Yousaf.

In Ms Sturgeon's case, the message must have been retained by someone else in the chat.

They're revealing because of their informality and their frankness, giving insights into what the politicians really thought, rather than their more polished and arguably more restrained public utterances.

Nicola Sturgeon describes Aberdeen Football Club's statement after some of its players caught the virus after breaching the rules as a "complacent abomination"

Meanwhile, in a separate conversation, Humza Yousaf is asking for clarification on the face mask rules.

The inquiry has questioned why, as health secretary at the time, he didn't understand them, but Professor Jason Leitch, the national clinical director, admits they were nuanced.

He denies he was offering a work around by suggesting Mr Yousaf should always have a drink in his hand to get around the regulations.

Instead he argues he was offering a means of compliance.

Lady Hallet returns to the issue of deletion of messages and says some of the tone of some of the messages she has seen express a "rather enthusiastic adoption of the policy of deleting messages".

Prof Leitch denies this and says that was not his position, he was following the guidance.

Lady Hallet says: "There also might be a suggestion that some of the people wanted to delete messages to avoid the messages being the subject of a Freedom of Information request.

"That would be wrong wouldn't it?"

Prof Leitch agrees and again says that was not his position.

"I never suggested or did that," he says.

The chair of the inquiry asks if, when the Scottish Covid inquiry was announced, did he continue following that guidance.

"I continued to follow the guidance as I saw it,"

Image source, Scottish Government

Prof Leitch tells the inquiry it wasn't all football shows and phone-ins. He says a lot of the communication was "very serious statements at the podium".

The clinical advisors "fitted in" to the former first minister's way of dealing with the media, he says.

They decided not to use slides like the UK government, but instead they started with data then took every question until they were done.

But he disagrees that the Scottish broadcasts "lacked gravitas".

Prof Leitch stressed they were more about empathy, the nature of the threat and what we people were being asked to do.

He points out "one of the most serious days I have faced as a professional" when he and Gregor Smith appeared together with the first minister to announce the second lockdown.

"Would it be fair to say that the Scottish government was not always as transparent as it could be in its communication about the pandemic?" asks Jamie Dawson KC.

The national clinical director says he tried to give all of the information he had when he had it, so the public would know what they were asking them to do.

Prof Leitch says there is transparency, but there's a balance about what you can say and when you say it, he explains.

"I, as an individual, tried to be as open and honest as I could."

He accepts communication could have been improved and he says the fear about the Nike conference was that people could be identified and confidentiality would be breached.

Prof Leitch says he spoke a lot about football because the most listened to radio programme in Scotland is a football show, which has half a million listeners.

"I appeared on it every week for 18 months... to get the message out to a very broad demographic," he says.

"Off The Ball is a two-hour Saturday lunchtime football show, but there was no football so they had to have something else to talk about, so they talked about Covid."

The BBC Radio Scotland show is presented by Stuart Cosgrove and Tam Cowan.

What are the learning points from Professor Leitch that the inquiry should consider, asks Jamie Dawson KC.

The national clinical director says he learned three things.

Firstly about behavioural science, to tell the public why before you tell them what. He says he probably didn't do that enough initially.

Prof Leitch then says there was something about groups that were harder to reach. He adds he spent time in the African and Polish radio stations for Scotland but admits he could have done more.

Finally, he says: "Sometimes I overspoke, sometimes I got ahead of myself.

"I was on a lot of shows a lot of the time."

Image source, PA Media

Prof Leitch says there were occasions when the country was opening up again "when there was, of course, nuance" about the rules.

Referring to the exchange with Humza Yousaf, Mr Dawson says: "If health secretary didn't understand the rules, what chance did anyone else have?"

Prof Leitch says he had the impression that hardly anyone followed the rule about masking when standing up during a meal, when dining was allowed unmasked.

He said the rules didn't cover "standing politely" if someone came to talk to you at the table.

He says he gave Mr Yousaf advice on how to comply with the rules on wearing a mask - by holding a drink at a drinks reception.

Mr Dawson refers to a message from then Health Secretary Humza Yousaf to Professor Leitch asking about advice for wearing a face mask at social occasions

In the message Prof Leitch tells him he should be wearing a mask if he is standing up but adds no-one else is doing it.

The national clinical director says he stood up at a social event and was pictured without a mask.

"So strictly speaking that was breaking the rules," he says, adding because it was a social function he thought it was legitimate.

Mr Dawson highlights a chat where Prof Leitch writes: "Just my usual reminder to delete your chat... particularly after we reach a conclusion."

The national clinical director responds that they were following Scottish government guidance.

He adds that once they had reached a conclusion, and that had been "fed into whatever mechanism was appropriate", then that the chat should be deleted.

Prof Leitch says there was an auto delete function applied to a group with chief medical officer Gregor Smith and Jim McMenamin, the chairman of the National Incident Management Team.

"The decisions we were coming to were being dealt with very, very quickly," he says and adds that he set the group up to get data before media appearances.

Prof Leitch says he is comfortable that he has followed guidance on what should be retained and what should be deleted.

Jamie Dawson KC turns to the WhatsApp chat group discussing the impact of the Delta outbreak in the immediate aftermath of the Scottish election in May.

He highlights Professor Leitch saying: "WhatsApp deletion is a pre-bed ritual."

He asks why the national clinical director thought it was appropriate to delete messages daily.

Prof Leitch replies: "It's a slightly flippant and it's an exaggeration.

"I didn't daily delete my WhatsApp."

He adds: "This was a flippant exaggeration in an informal messaging group and it wasn't done every day before I went to bed."

Prof Leitch says that in his job he was getting hundreds of emails and messages every day.

He tells the inquiry that the volume of information can be "overwhelming" and he tries to "manage today's messages and emails today".

"I try and work an inbox zero way of working," he says. "That is the only way I've found to mange the level of information that I do. It remains my way of working today."

Jamie Dawson KC asks if it was important to keep a record of decisions and how they were made and Prof Leitch agrees.

He presumed from the outbreak of the pandemic that that there would be some sort of inquiry, he adds.

The counsel of the inquiry turns to Prof Leitch's use of messages in the pandemic and asks what his understanding of the Scottish government's policy on the use and retention of informal messaging such as WhatsApp and text messages.

Prof Leitch replies: "As you've heard the record retention policy was that you could use informal messaging systems for Scottish government business.

"If you did you should ensure that any advice or any decisions or anything that should be in the corporate record should be placed in that corporate record by e-mail, briefing etc, and then you should delete the informal messaging and that's the guidance that I followed."

The national clinical director explains the core advice would be added to the corporate record and then WhatsApp messages could be deleted.

"There was a requirement to keep salient information and put it in the corporate record."

He adds once advice had been constructed it needed to be placed in an e-mail but beyond that any discussions did not require to be retained.

Jamie Dawson KC asks about the recommendation for a firebreak lockdown during the October holidays.

He asks what changed between the two documents giving advice on a firebreak.

Prof Leitch says they recieved more data and modelling throughout the day and then "adapted our advice".

There was a new set of interventions they then recommended, he adds.