If the purpose of the UK Covid inquiry is to "learn lessons" for future pandemics, then lesson number one is probably to make sure we never put Boris Johnson in charge of any future national crisis which depends on scientific literacy and decisiveness.

Evidence this week has ranged from the inane to the frankly disturbing, and the former Prime Minister will have difficult questions to answer when his turn comes to be grilled by Hugo Keith KC - something that is expected to take place before the end of this year.

There was the revelation from Dominic Cummings' witness statement that Johnson had once shared a YouTube video of "a guy blowing a special hair dryer up his nose 'to kill Covid'", asking his Chief Scientific Adviser Sir Patrick Vallance and Chief Medical Officer Sir Chris Whitty "what they thought".

READ MORE: What's happened to life expectancy in Scotland - and why is it so much better in Ireland?

Then there was his puzzling grasp on life expectancy.

In October 2020, in a WhatsApp exchange with Downing Street's director of communications Lee Cain, the inquiry heard that Johnson remarked that he was "slightly rocked" by data on Covid fatalities indicating that the median age of patients dying from the infection was 81 for men and 85 for women.

"That is above life expectancy. So get Covid and live longer," he wrote, adding that “there are max 3m [three million people] in this country over 80”.

He was arguing against a second lockdown to protect the NHS.

While the elderly certainly bore the brunt of Covid mortality, it was also true that some 40% of those who died in 2020 were under-80 and that life expectancy at birth is not a relevant measure in this context: people who have lived into their eighties have already defied the odds health-wise and could therefore expect to live many more years.

The Herald: Boris Johnson was said to have been 'obsessed with older people accepting their fate'Boris Johnson was said to have been 'obsessed with older people accepting their fate' (Image: Andrew Parsons/Number10 Downing Street)

However, the inquiry also heard - from diary excerpts penned by Vallance in October and December 2020 - that the PM was "obsessed with older people accepting their fate", and that he was "not entirely sure" that he disagreed with the opinion of some Tory backbenchers that Covid was "just nature's way of dealing with old people".

On another occasion Johnson is said to have told a Cabinet meeting in December 2020 that he agreed with the view that "we should let the old people get it and protect the others".

READ MORE: Covid was 'just nature's way of dealing with old people', inquiry told

WhatsApp messages from Simon Case - the former head of the UK civil service - described the PM as “Trump-Bolsonaro level mad and dangerous” in July 2020 as he pushed to declare Covid "over", end social distancing and reboot the economy despite signs that a second wave was underway.

According the Cummings, "pretty much everyone" in Downing Street referred to the PM as a "trolley" due to his habit of chopping and changing his mind.

The overall picture which has emerged is that Number 10 - the nerve centre of the UK's pandemic response - was a hotbed of infighting, machismo, and "breezy" British exceptionalism which fostered a sense everything would be okay, until it wasn't.

The bigger question is to what extent the UK's handling - or mishandling - of the pandemic response led to avoidable deaths.

The Herald: Jacinda Ardern was praised for her 'clear and consistent' leadership on Covid, but resigned earlier this year amid a growing backlash over the state of New Zealand's economyJacinda Ardern was praised for her 'clear and consistent' leadership on Covid, but resigned earlier this year amid a growing backlash over the state of New Zealand's economy (Image: Getty)

No country acted perfectly, and none has escaped the consequences of its decisions.

Take New Zealand: praised for its "clear, consistent" leadership and stringent border closures which kept Covid out during 2020 and 2021 and actually reduced its overall mortality rate, it is now wrestling with the economic harms of a 43% increase in government debt (versus 15% in the UK) and its highest inflation since 1990.

This is partly due to the effects of lost tourism revenue and emigration of labour out of the country during the shutdown.

Sweden never closed its schools and only briefly kept older children out of classrooms. Rather than government-mandated lockdowns, Swedes were advised to limit their social interactions, mask, work from home, and self-isolate when sick (employees received 80% of their salary while they quarantined).

Voluntary compliance was high, and while they suffered higher excess mortality rates than their stricter Scandinavian neighbours they still fared better than the European average and there is evidence that the impacts on educational attainment, depression, and anxiety in children and young people has been much less.

However, Sweden started off in a much better position than the UK, with far lower obesity rates and population density as well as much higher levels of trust in government.

READ MORE: Devi Sridhar: Yes, Sweden has lockdown lessons for the UK - but probably not what you expect 

In terms of cumulative excess deaths per million population (from all causes) over the three and a half years since the World Health Organisation declared Covid to be a global emergency, the UK is somewhere in the middle internationally: behind the US and Brazil (of the Trump/Bolsonaro comparison), similar to Spain, worse than neighbouring Ireland, but nothing like as bad as Russia.

The Herald: Cumulative excess deaths from all causes, per million people, up to October 1 2023Cumulative excess deaths from all causes, per million people, up to October 1 2023 (Image: Our World in Data)

If it hadn't been for the UK's early and rapid Covid vaccination programme, things may have been much worse - at least in in mortality terms.

Harrowing evidence currently being gathered by the Scottish Covid inquiry on the impact of the pandemic on ordinary people lays bare just how awful and wide-ranging some of the other consequences have been, from long Covid and domestic abuse victims confined with their attacker to the carers plunged into despair as they tried to look after loved ones alone and children with autism driven to suicide attempts after their routine vanished.

The thing about the WhatsApp evidence led at the UK inquiry is that it sheds light on what was going on "under the bonnet" in government: the prevailing attitudes of the ministers and officials in charge, and how competent they were perceived to be.

It underlines why we deserve to have equivalent evidence from the Scottish Government.

While hamstrung by UK decisions on issues such as border closures and funding for lockdowns, ministers at Holyrood still set the rules on everything from testing policy to Covid mitigations in schools.

If we are finally seeing the grim reality of the Johnson administration, then it is only right that Sturgeon et al face the same scrutiny.