Things fall apart. Just a little, at any rate. Moments after the latest Cobra meeting had broken up, Scotland’s first minister, Nicola Sturgeon, went rogue and gave her own press conference.

The coronavirus pandemic had gone beyond the “containment” phase and into “delay”. People with a dry cough and a fever should self-isolate. Large gatherings of more than 500 in Scotland would almost certainly be banned from Monday. Enough time to make sure the Old Firm derby between Rangers and Celtic could be played on Sunday.

A little over an hour later, Boris Johnson emerged into the familiar setting of the Downing Street state room to give his third coronavirus presser inside two weeks. There will be plenty more to come.

His message was pretty much identical to Sturgeon’s, other than to declare that sports events and concerts would be going ahead in the rest of the UK for the foreseeable future. His irritation at being pre-empted by the first minister on further measures was mostly kept in check. Only a barb at the lack of resilience in the Scottish health service betrayed his feelings.

Boris was here to tell the country we were in for a long haul, but he already looked on his knees. He has aged appreciably over the last few weeks. The eyes are puffier, the bags baggier and the complexion pastier. Being prime minister is turning out to be a lot less fun than becoming it. He looks sleep-deprived.

Q&A How can I protect myself and others from the coronavirus outbreak? Show Hide The World Health Organization is recommending that people take simple precautions to reduce exposure to and transmission of the coronavirus, for which there is no specific cure or vaccine. The UN agency advises people to: Frequently wash their hands with an alcohol-based hand rub or warm water and soap

Cover their mouth and nose with a flexed elbow or tissue when sneezing or coughing

Avoid close contact with anyone who has a fever or cough

Seek early medical help if they have a fever, cough and difficulty breathing, and share their travel history with healthcare providers

Advice about face masks varies. Wearing them while out and about may offer some protection against both spreading and catching the virus via coughs and sneezes, but it is not a cast-iron guarantee of protection Many countries are now enforcing or recommending curfews or lockdowns. Check with your local authorities for up-to-date information about the situation in your area. In the UK, NHS advice is that anyone with symptoms should stay at home for at least 7 days. If you live with other people, they should stay at home for at least 14 days, to avoid spreading the infection outside the home.

The responsibility is weighing heavy. He isn’t used to being held accountable for anything – his whole life up till now has been an exercise in self-indulgence – but he knows that he will be forever judged by the decisions he makes now. The smirking clown might have worked well for Brexit, but now the country is demanding a serious leader.

Just for the moment, he is having to fake it to make it. And it’s just about working. The man who has a psychological aversion to bad news is having to level with cosmological truths.

The soft-soap, occasional comic asides and veneer of self-confidence have given way to something more real. The sense of despair and self-doubt that Boris has worked so hard throughout his life to keep internalised is now etched into every line of his face, drenched in every sentence he haltingly utters. Having to tell a lot of people they might die can do that to you.

Play Video 1:46 Coronavirus: Johnson warns 'many more families are going to lose loved ones' – video

Sensibly, Boris had once again come flanked by the new de facto joint prime ministers – the chief medical officer, Chris Whitty, and the chief scientific adviser, Patrick Vallance – and he rightly deferred to them on matters of science and epidemiology. Both men were hugely impressive: when they were sure of the numbers they said so, and when they weren’t they also said so.

There was no artifice, no bullshit. Just cold hard truths. We were about four weeks behind Italy and the virus might not peak for nine to 14 weeks. There was almost something reassuring in their lack of reassurance. For the first time in years, the public were being treated as adults. Just about the only question ducked was the one about what constituted being “old”. Something of personal concern to those of us in our early 60s.

Inevitably, most of the questions from the media were about whether the UK was doing enough. Other countries were closing schools, closing borders, closing down large public gatherings, closing travel. We were just advising people with symptoms to stay indoors for seven days, schools to cancel overseas trips, and people to wash their hands. With the proviso we would probably be implementing stricter measures at a later date.

Not for the first time, it felt as if many in the country were ahead of the government in their response to the coronavirus. Many people had seen what was going down in Italy and had already cancelled large social gatherings, non-essential travel and were making plans to work from home where possible. Better safe than sorry.

Boris, Whitty and Vallance were as one, though. The science was on their side. Which presumably meant that it wasn’t on the side of all those countries who had made more radical, earlier interventions.

The three amigos were insistent that if we moved too soon, people would get bored of taking the proper precautions when the pandemic spiked. Not everyone in the room was wholly convinced. The idea that everyone would be running round the streets coughing over one another when they knew the risk of infection was at its highest just because they had already been cooped up for a few weeks seemed far-fetched.

But the science was the science. And Boris was banking on his science being the right science. He wasn’t to be forced into doing anything before it could be shown to have a noticeable effect.

In the meantime, he wished everyone well and asked for everyone to look out for one another. Especially the vulnerable and the elderly. Brexit was never going to bring the country together. But coronavirus just might. As he left the press conference, Boris had his fingers firmly crossed. So did I.