t the time that he made an emergency national TV broadcast to declare the lockdown, Boris Johnson thought he was taking one of the biggest decisions of his premiership. In truth, it was a simple one – at least it was compared with the choices he has to start making this week. Attempting to ease out of restrictions without reigniting the epidemic will be both the most uncertain and most perilous phase of this crisis. The decisions he makes are ones that will define how he is judged by history. Get it right and he may or may not be rewarded with some public credit. Get it wrong and the blame will likely chase him all the way to the next election. There was a hint that he knows this in the “I’m back at my desk” news conference that marked his return to Number 10. He produced some characteristically Borisovian metaphors involving tunnels, peaks, sunlight and pastures. Then his language suddenly turned tentative when it came to the actual detail about when and how the government intends to lift elements of the lockdown. He talked not of a “battle plan”, the sort of flourish a confident Johnson would have gone for, but a “menu of options”. He didn’t mention an “exit strategy”, a phrase that Number 10 has banned ministers from using. There won’t be a full exit for a long time and there isn’t yet anything worthy of the description strategy. There is general agreement within government that open spaces are early candidates for an easing of rules, while gyms and bars will be the last to reopen. There are very live debates within cabinet about everything in between. We are most likely to see cautious moves to test what can and cannot be done safely. One person at the heart of decision-making puts it like this: “What you can’t do is release loads of measures all at once, only to find that there is a resurgence and you have to put them all back on again. You can’t go too fast and you’ve got to monitor and measure as you go.” This points to a very gradual easing of lockdown with the government retaining the option of reimposing restrictions if infection levels flare up. Franklin D Roosevelt addressed the Great Depression of the 1930s with what he called “bold experimentation”. What we will see from the government over the days ahead is tremulous experimentation. The choices confronting the prime minister are not ones he would willingly make. One colleague closely involved in the government’s internal debates reports: “Boris being Boris, he wants to end all the restrictions and get the economy fired up again without a single life lost. He can’t have that, of course.” In the coronavirus, the Tory leader has encountered an enemy that confounds the have-your-cake-and-eat-it philosophy by which he has led his life and practised his politics. The choices are not easy and he will have to navigate them half-blind because there is still much that “The Science” is currently unable to tell us about this novel disease. It has become one of the ministerial mantras of this crisis that they are “following the science”. That is obviously preferable to the opposite. We can at least be thankful that we do not have a national leader whose wildly reckless interventions have included musing that people might find a cure by injecting themselves with disinfectant. A revival of respect for expertise has been a beneficial consequence of this crisis, but it doesn’t relieve politicians from the responsibility to make the toughest calls. Scientific advisers advise; ministers decide. This is even more the case because opinion among scientists has never been homogenous and there is still much that they don’t fully understand. Immunity is one of those unknowns. There has been some optimistic news from South Korea in the past few days, but there is not yet certainty about whether infection leads to immunity, how long immunity might last and how strongly, and whether people can be immune and at the same time be carriers of the disease. Another big question mark hangs over the role of children in transmission. If they can be as infectious as adults, that is very bad news, with major implications for when schools can be reopened. If children are not as infectious as adults, that is much more encouraging. The swiftness with which restrictions can be eased is hugely contingent on the rate at which the virus is spreading. Sir Patrick Vallance, the chief scientific adviser, says it is believed that the average reproduction rate – R – in Britain is now somewhere between 0.6 and 0.9. In decimal points, that is a small difference. In terms of the options it offers the government, that is a vast range. The closer R is to 1, the greater the hazard that a lifting of restrictions will trigger an explosion of infections. The closer R is to 0.5, the more rapidly the epidemic will reduce in strength and the more easing ministers can dare risk. The government will improve its chances of acting safely if it can put together a reliable system for testing, tracking and tracing infection. Matt Hancock (sort of) achieved his target of 100,000 tests a day at the end of last week, but most expert opinion believes that this needs to rise to more like the 250,000 tests a day once pledged by the prime minister. The required number of tests greatly depends on how prevalent the disease is among the population – and the government doesn’t know that either. They hope to start solving that mystery through the recently launched mass survey programme. The first data started to come in this weekend. The government’s “five tests” for easing the lockdown are not as definitive as they pretend to be. They were put together while the prime minister was out of action in an attempt to dampen the growing clamour from Tories for a plan to end the lockdown before it completely suffocates the economy. That pressure is still being exerted from the Conservative benches. Mostly confined to their constituencies, Tory MPs are paying more attention than usual to their inboxes and voicemail and both are overflowing with local business owners screaming that they are going bust. One senior Tory says: “In six months’ time, the argument won’t be about whether we should have shut the pubs a week earlier. The argument will be about how we got into a god awful recession.” There are evident differences among the cabinet. Some of the positions taken by ministers can be explained by the seats that they occupy. As health secretary, Mr Hancock’s overriding priority is to avoid the NHS collapsing under the stress of an overwhelming number of coronavirus victims. He’s always believed, and not wrongly, that this scenario would not only destroy his career, but irretrievably shatter the reputation of this government. As chancellor, Rishi Sunak’s central focus is on the tremendous blows being inflicted on the economy and the vast amount of red ink splashing on to the public finances. But Mr Sunak’s allies report that he fully understands that it would be a disaster to relieve restrictions only for a resurgence in the disease to force the government to clamp a full lockdown back on again. Colleagues of Mr Hancock say that “Matt understands we will need some kind of economy left at the end of this” if the health service is to be funded in the future. Britain has one advantage. We were hit by the pandemic later than many other countries and this offers the opportunity to watch and learn from the experiences of those who are ahead of us in trying to reopen their societies. The lessons are cautionary. Having thought it had beaten back the disease, Singapore has been confronted with another outbreak. Since Germany started to lighten its lockdown, there appears to have been a resurgence of infection in some parts of the country. This strengthens the hand of those in government arguing for a gradualist approach. The public surprised ministers by being highly compliant with the lockdown and another unknown for the government is how people will respond to an easing. Many are desperate to get back to work because they need to earn money. At the same time, majorities of respondents tell pollsters that they are wary of leaving their homes and nervous about using public transport again. Over the coming weeks, millions of Britons will be weighing the risks posed by the disease against the fear of losing livelihoods. They will be making what could be life-or-death decisions on the basis of very incomplete information. It may or may not be a consolation that their prime minister is facing the same predicament. • Andrew Rawnsley is Chief Political Commentator of the Observer