The Prime Minister’s broadcast to the nation last Sunday evening featured five main slides.  The first showed the Government’s five Coronavirus tests.  The second, the words: “Covid Alert level = R (rate of infection) + number of infections”.

The third displayed this R level applied to a kind of speedometer, with the lowest of five bands coloured green and the highest red – with restrictions on the public kicking in as the dial needle approached the red band.  (There was later a variant which showed this slide set against a map of the United Kingdom with assorted Coronavirus hotspots.)

The fourth showed those green to red level levels in bar form, with each described as an “alert level”.  The fifth showed an uneven hump with a long slope, like a wave, which represented a gradual slide from severe to less severe constraints on public activity.

The point of all this description is to show that although, at one level, Ryan Price is right (“what do you want, a full handbook, to tell you what to do?”), and much of Boris Johnson’s new plan is simply common sense, at another it is all just a bit more challenging.

With its accompanying dials, bars, humps and speedometers, easing a lockdown will be more tricky for Ministers than simply imposing one.  The where you’re going to of the plan may be straighforward, but the how to get there is more complicated.

So if you thought that the Government’s task has been difficult so far, or that its handling of the Coronavirus has been controversial, you ain’t seen nothing yet.  The Prime Minister suggested on Sunday that we have collectively reached the top of the mountain, and now face the daunting prospect of the climb down.

But the way we see it, the British people may not yet have staggered even to the outcrops of K2 – since the prospect of a vaccine, or effective treatments, or herd immunity remain shrouded in mist at the summit (though there may be good news on antibody tests).  And Ministers come to the next stage of the climb winded, for three main reasons.

First, for one that can’t reasonably be claimed to have been their fault.  Namely, that the playbook prepared for government when the pandemic came was a flu-style one, into which the idea of herd immunity was written, rather than a Sars-type one, which would stress testing and tracing, and the quarantining of those infected.

Second, for taking up a mass tracing and testing policy towards the end of last month, some eight weeks after the virus outbreak began to gather critical mass in Britain, in its third iteration of policy.  The date of the change is a matter of record and can’t credibly be disputed.

The third reason is perhaps the most exhausting and certainly as yet unproven.  It is the claim that Ministers and the NHS, in preparing hospital beds for an influx of virus cases, emptied them by sending a mass of infected but untested patients to die in care homes, thus sending UK death rates to the top of the league.

These international tables are riddled with problems and, for the rest, we shall see what the eventual inquiry brings with it.  What’s certain as this third phase of dealing with the Coronavirus begins (we’ve had almost normal; then abnormal; now, “the new normal”) – the Government has less room for manoeuvre than it did before.

True, most voters appreciate the scale of the problem, aren’t lost in the Twitter echo chamber, and don’t envy Johnson his task: many will not have forgotten that he has been through intensive care himself recently – and so is literally leading from the front.

Nonetheless, the lotus-eating experience of furlough – for some, anyway – can’t ultimately shut out the brutal economics of Covid-19, with its further waves of blighted schooling, bankruptcies, illness and job losses to come.  The tower of the Conservative poll lead may be built on sand. And Keir Starmer leads a more effective if unscrupulous Opposition

At any rate, the Government has now settled on a route and, though it may not be able afford many more mistakes, the good news is that the path it has chosen may take us all nearer where we need to go.  That’s to say, if not to the top of the mountain, then at least higher up its slopes.

Much will depend on whether Ministers can make testing and tracking work.  Some believe that the app is a kind of technological red herring, and that the real issue is that the Government may be planning for some 30,000 fewer trackers than it needs.

It may be that this calculation is wrong, or that Ministers are able to scale up numbers quickly, or that the incidence of cases falls swiftly.  In which case, there will be an adequate England-wide capacity to test, track and quarantine.  But though the capability would be national in its scope, the applicability wouldn’t necessarily have to be.

For testing on large scale would show the R-rates that matter: in other words, not a single UK-wide figure, the use of which is limited, but different local ones, showing where the virus is replicating fastest and among whom.  This would allow the opening-up of much of the economy on a regional, area or local basis.

Such a process would side-step the sterile debate about lockdown: after all, South Korea, on which the Government is modelling its policy, has been more limited.  Admittedly, we are starting with higher levels of the virus.  But if the testing plan works, lockdown could stop being a national all-or-nothing business, and become a local mix-and-match one.

How would the transfer of people from fully lockdowned areas to partially lockdowned ones be managed – with the risk of local R-rates being driven up again?  In part by opening some sectors and facilities, such as schools, before others, such as restaurants and hotels.  Though movement might well still happen on a significant scale.

Which tees up a big debate: is it better for the whole UK (or at least England) to move uniformally in lockstep at the pace of the most virus-threatened areas – even if that slows desperately-need economic revival – or to allow the ones that are less seriously affected to stride ahead, and move substantially out of shutdown?

If the testing, tracing and quarantine policy works, this is a debate that is surely bound to happen.  It would be more to the practical point than another: whether the NHS now has enough capacity to cope with any second or subsequent waves?  Bernard Jenkin, citing statistics, says no. Raghib Ali, with his epidemiological experience, isn’t so sure.

The political weather for Johnson has been rougher than it was at the end of February.  And one can see how his political enemies – the Remaniac residue; Starmer; Nicola Sturgeon; his internal opponents – are setting him up for failure.  But there is opportunity as well as danger: a path if not to conquering the virus then at least to checking it.