LONDON—Earlier this month, while other countries were deploying powerful counter pandemic measures, Boris Johnson paid a visit to Kettering General Hospital an hour and a half north of London.

Afterwards, he boasted that he had taken no precautions. “I’m shaking hands continuously,” he said with a smirk during a press conference on March 3 that was called ostensibly to warn people of the upcoming threat. “I was at a hospital the other night where I think there were coronavirus patients and I was shaking hands with everybody, you will be pleased to know, and I continue to shake hands.”

It soon transpired that Johnson did not—in fact—shake hands with any patients and it is thought there were actually no COVID-19 sufferers at the hospital at the time (the first coronavirus patient was to die there two weeks later).

Johnson’s badinage was to be taken seriously, but not literally.

The message he was delivering to the people of Britain, who had just given the Brexit prime minister a huge electoral mandate, was that we didn’t need to do anything about this virus beyond some judicious additional hand washing.

Remarkably, that was an official government position that would hold for two further weeks, as Johnson declared that crowds at sporting events posed no particular risk and resisted calls to shut the schools.

The U.S. and much of Europe were implementing widespread lockdowns; the opposition Labour party was demanding tougher restrictions; and there was even talk of a revolt within Johnson’s own Conservatives.

By the time schools had closed and Johnson finally ordered Britain’s pubs and restaurants shuttered on March 20, there were more than 200,000 confirmed coronavirus cases around the world and over 10,000 fatalities.

Why were the British so slow to react? Professor Neil Ferguson of Imperial College London, a government adviser whose bombshell report on the likely impact of coronavirus stiffened policy in London and Washington, D.C., admitted this week that behind the scenes there had been a dispute about how much to protect the economy versus ensuring that the disease was suppressed.

Britain initially pursued a policy of allowing the disease to spread, relatively untested and unchecked. Sir Patrick Vallance, the Chief Scientific Adviser, defended Johnson’s inaction by explaining that the measures adopted by countries like South Korea, where widespread testing allowed every case of COVID-19 to be traced and tracked, also had downsides.

“If you suppress something very, very hard, when you release those measures it bounces back and it bounces back at the wrong time,” he said on March 13. “Our aim is to try to reduce the peak, broaden the peak, not suppress it completely; also, because the vast majority of people get a mild illness, to build up some kind of herd immunity.”

Matt Hancock, Britain’s Health Minister, would later deny that “herd immunity,” achieved when more than 60 percent of the country has already had it, had ever been part of the strategy.

An extraordinary report in this week’s Sunday Times explained what it said was the original strategy inside No. 10. Johnson’s top adviser, Dominic Cummings, was reported to have outlined the approach at a private gathering at the end of February, which was characterized by people at the event as “herd immunity, protect the economy, and if that means some pensioners die, too bad.”

On Friday morning, the prime minister announced he was suffering from a “mild” case of COVID-19. Hancock announced a few minutes later that he had also contracted the virus. Prof. Ferguson went down with it earlier in the week.

Soon after Johnson’s announcement, Cummings was seen racing out of No. 10 and running out of the gate at the back of Downing Street.

Yet the British strategy had won influential admirers in the U.S.

Fox News’ Steve Hilton, a Brit who held a similar position to Cummings under Conservative Prime Minister David Cameron, has been prominent among the right-wing pundits pushing President Donald Trump to use the same strategy in the U.S.

“Our ruling class and their TV mouthpieces whipping up fear over this virus—they could afford an indefinite shutdown. Working Americans can’t. They’ll be crushed by it,” he said on his Fox News show this week. “You know, that famous phrase? ‘The cure is worse than the disease.’ That is exactly the territory we are hurtling towards. You think it is just the coronavirus that kills people? This total economic shutdown will kill people.”

Trump appears to have been listening.

The president is apparently toying with the idea of re-opening American businesses by Easter even as the U.S. overtakes China as the nation with the most cases of coronavirus and a death toll that has raced past 1,300.

Thanks to terrifying analysis of the scale of the carnage if the virus was allowed to spread unchecked—by Prof. Ferguson and others—Britain has now adopted a strategy that is more in line with other European countries, implementing a lockdown and ordering the closure of thousands of non-essential shops and businesses.

Johnson has struggled to get the words out. In press conference after press conference he has moved only gradually towards the shutdown, and seemed reluctant at every turn to command the British people to adopt social distancing and push the economy into the deep freeze. The measures run totally counter to his socially liberal, small-government instincts, and it’s no surprise that the country didn’t take him seriously at first.

It was only after last weekend when Brits flocked to parks and beaches to enjoy the spring sunshine, and the Conservative Cabinet threatened “a fullscale mutiny” that Johnson finally ordered people to stay in their homes unless it was essential to go outside.

Even when he’s trying his hand at crisis-management, Johnson’s clownish instincts return to the surface. On a call begging the private sector to step in and help, the prime minister reportedly joked that the project to build more life-saving ventilators should be known as “Operation Last Gasp.”