A pandemic is testing global leadership and its capacity to rise to the challenge of “the worst public health crisis for a generation”. To some surprise, the man who said that is addressing the emergency in a more mature fashion than many anticipated when it first began to unfold. Boris Johnson has abandoned the “invisible man” act for which I mocked him a fortnight ago and located the serious side of his character. The pantomime Johnson has been retired from public spectacle and replaced with the sombre Johnson we now see at news conferences. At his most recent, he struck an appropriately sober tone when he warned: “I must level with the British public: many more families are going to lose loved ones before their time”, words prime ministers usually don’t expect to utter outside wartime. Candour, not a quality always associated with this prime minister, is essential. Fear, panic and conspiracy theories are fomented when people suspect that their leaders are not telling them the truth. The Opinium poll that we publish today suggests that more people than not have confidence in the government’s handling of the coronavirus crisis, but the margin is not a very solid one.

The prime minister has been flattered by comparison with Donald Trump. His multiple flaws are being pitilessly highlighted by a crisis that a man who does not believe in scientific evidence or international cooperation is hopelessly ill-equipped to handle. Variously dismissing the coronavirus as “a hoax” cooked up by his opponents to deny him re-election or no worse than the flu, he has swung from juvenile denialism to blaming it on foreigners and Democrats. Then he suddenly announced travel bans and declared a “national emergency”.

The ineffable American president is the quintessential example of a stretch of world history in which populist blowhards have prospered at the ballot box by stoking division, promoting polarisation, scorning expertise and championing ignorance. This crisis, one that now touches every continent on Earth apart from Antarctica, demands leaders who are willing to listen to professional advice, capable of fostering national cohesion at a time of emergency, and skilled at seeking international cooperation. The luckier countries will be those blessed with competent, honest and intelligent leadership. One of the possible positives to come out of this crisis – I put it no higher than possible at this stage – is that it will decrease the public appetite for bombastic charlatans and increase demand for serious leaders who respect expertise. If it does, that will be bad for populist hucksters more generally.

The hope is to reduce the scale of the spike and delay it to a warmer month so that the health service isn't overwhelmed

Mr Johnson has often aped Trumpian populism when he has seen political advantage in doing so, but he is smart enough to grasp that something more grown up is now required. People present at Cobra meetings and other decision-making moments generally report being impressed by the way he conducts himself. I asked one witness, who is not an instinctive cheerleader for this prime minister, how they thought he was doing. The reply came: “Pretty well. He is listening intently to the science.” In this respect, Dominic Cummings, his chief adviser and a fervent admirer of science, is acting as a positive influence on the prime minister, rather than a baleful one. Whenever he addresses the country from the state dining room, he has come flanked by Sir Patrick Vallance, the government’s chief scientific adviser, and Professor Chris Whitty, the chief medical officer. Thrust into the spotlight in a way neither man can have anticipated, they have both impressed with the clear and calm way they have talked to the nation. They can explain the reasoning for the strategy and how it is evolving with much more credibility than any politician. The polls tell us they will be much more likely to be believed. The government’s senior scientists also serve as the prime minister’s human shields against accusations that he is acting out of ideological fixations or for partisan advantage. No wonder he is clinging to them.

The past few days have brought both more clarity and more controversy about their strategy. There is still consensus around one key component – to try to spread out the rate of infection: “flattening the peak”. The hope is to reduce the scale of the spike and delay it to a warmer month so that the health service is not overwhelmed with patients requiring critical care. In his budget, an event all but eclipsed by the crisis, Rishi Sunak promised the NHS “whatever it takes… millions or billions” to tackle the coronavirus, but you can’t spend that money overnight. The NHS needs to increase its intensive care capacity, but that requires more staff, more equipment and more time. The crisis in Italy, whose leadership was slow to realise that they had a problem and who have now imposed an almost total lockdown of the entire country, has shocked ministers. It is widely assumed that Britain is about four weeks behind Italy in terms of infection, though that doesn’t mean we have to end up in the same grisly place.

There is not consensus, but mounting controversy, about another critical element of the government’s strategy. Britain has adopted a strikingly different approach to the many other countries that are implementing faster and more sweeping programmes to curtail human contact. These include Ireland, France and Belgium, all close neighbours.

That has fuelled the rising pressure on the prime minister to take much more stringent steps here. The pressure is coming both from Labour and from within the government’s own ranks. Jeremy Hunt, the former health secretary, has been the loudest voice asking why we are not seeking to emulate Asian states, such as Singapore and South Korea, that seem to have had some success in snuffing out the spread of the virus.

The government is moving towards banning sports fixtures and other mass gatherings, but is still resistant to a more comprehensive shutdown. The scientific reasoning behind Britain’s approach is that more draconian steps won’t make that much difference at this stage, are not sustainable over the longer term, and may well turn out to be counterproductive because it will lead to a second wave of infections when restrictions are eased – possibly in winter, when the NHS is most stretched.

Sir Patrick has lucidly explained what the strategy is designed to achieve. It expects those on whom the disease has mild effects, the great majority, to be gradually exposed to the virus, building up “herd immunity”. Over time, this will lower the risk of infection for the vulnerable. While this is going on, they will do what they can to protect those for whom the coronavirus could be fatal. Perhaps the most important advice given by the government last week was the simplest. That was to tell people who have flu-type symptoms, however slight, that they should stay at home for seven days. “That’s not trivial,” says one of those involved in this decision. “That is a significant amount of social distancing.”

Faced with an invisible menace with extremely visible impacts, a clamour for instant and total shutdowns is understandable. But it comes accompanied by the danger that kneejerk responses by frantic governments can end up doing more harm than good. One scientist drew my attention to the Fukushima nuclear plant disaster in Japan in 2011. Later studies found that around 20 people died from radiation. Many more, about a thousand, lost their lives as a result of the decision to evacuate: casualties of car crashes, heart attacks and other medical emergencies triggered by trying to clear the area in a rush. Sometimes the obvious reaction to a crisis will not be the correct one.

Many lives depend on getting this right. The government can’t be blamed for the virus, but there will be fierce scrutiny of its responses. There are risks with the strategy it has adopted – and huge ones for the reputation of Mr Johnson if the public concludes that his handling of the crisis led to avoidable deaths. There are hazards, too, with the alternative approaches. Various models for tackling the pandemic are now being live trialled around the world by governments of many different complexions and levels of competence. It will likely be a year or so before we will gain an understanding of which of the plans was the smartest. My conversations have convinced me that the British approach is rooted in scientific logic and a careful calibration of the different risks. I’m no epidemiologist so I won’t pretend to be a qualified judge of whether they are doing the right thing. I am persuaded that they are sincerely endeavouring to do the right thing.

• Andrew Rawnsley is Chief Political Commentator of the Observer