Bernard Jenkin MP was Chair of the House of Commons Public Administration and Constitutional Affairs Select Committee 2010-2019, and is nominated to be Chair of the Liaison Committee. He is MP for Harwich and North Essex.

Jim Callaghan had an adage: “Nothing in politics is as good or as bad as it first appears to be”. We need a dose of that kind of wisdom now.

Boris Johnson’s address on Sunday evening was long trailed, but delivered in just a few minutes. It provoked an immediate wave of criticism from all sides for its imprecision: yesterday’s press and the BBC coverage of reaction to the broadcast were anything but flattering or helpful.

The Prime Minister didn’t attempt to varnish the truth of the precarious position we now face. He did not patronise the public by holding back the grim detail behind the thinking: the all-important need to bring the ‘R’ number below one, or the doubt about how this can be achieved while also relaxing the lockdown. He did not pretend that there could be any certainty about what measures will have to be taken when because he knows that it is hard to judge what measures will have what effects.

In doing this, he took the British people into his confidence. He demonstrated his candour and they will trust him to make the right judgements. As he subsequently told the House of Commons on Monday, he trusts people’s “good, solid, British common sense”.

By comparison, much of the media and his political opponents see this speech as weakness. They have now started to open fire with the kind of political criticism and opposition for its own sake that was more common before this crisis. They are exploiting what the Prime Minister admitted is a challenge: moving from a message as simple as stay at home to one with far more complexity. The assumption behind these attacks is that either excessive caution or (from some in my own party) a quicker liberalisation would win acclaim.

The attacks on the Prime Minister are shamefully aided and abetted (whether intentionally or not) by publicised divisions amongst senior ministers. We have grown inured to the idea that Sunday journalists are provided with anonymous briefings by government insiders, exposing personal rivalries, but this really must stop.

Yes, much of the science is contested, but a cold look at the agreed facts and at the economics of the lockdown, with intelligent appreciation of the mood in our cities, towns and villages, will find the Prime Minister has judged it right.

As my recent article for this website explained, our route forward is hugely dependent on our ability to track, trace and isolate cases of Covid-19 as quickly as possible. As people start to come out of their homes, the ‘R’ number is likely to rise above one. If it went to 1.2, that would mean that the current 136,000 cases in England would increase by 20 per cent compound every five-to-ten days. In the space of a few weeks, we would run out of ITU beds – and another much harsher lockdown would have to follow.

Without altering people’s behaviour, the only way to reduce ‘R’ while opening up is to be much better at identifying infected individuals and their contacts before they infect others. Otherwise, self-isolating and quarantining alone will mean millions staying home and being unable to work, meaning the economic damage we hope to avoid will take place anyway – even before accounting for the human toll of the virus.

This must mean a substantially increased number of contact tracers – even above the Government’s target. The European Centre for Disease Control estimated that every identified Covid-19 case has 90 contacts that need tracing – approximately 13 per day in the week prior to diagnosis.

Early analysis from Univeristy College London calculates that effectively tracing each of these 90 people would require the work of six people for a full day. If, as we open up, our daily contacts remain at just half of their pre-crisis level, we will still need three contact tracers for every daily infection.

While we are diagnosing approximately 6,000 new cases every day, we know the true number is closer to 15,000. That translates to 45,000 contact tracers: far higher than the 18,000 target the Government has announced it is recruiting.

It is possible, as Singapore and Taiwan have shown, to reduce the burden on contact tracing with mobile apps, such as NHSX currently being tested in the Isle of Wight. But these apps come with their own problems that the Government must solve. Although 80 per cent of people in the UK have smartphones, Office for National Statistics data shows that six in ten of those over the age of 65 do not have access to the internet via such a phone.

One in eight of the lowest income quintile do not have mobile phones. Relying too much on an app to replace manual contact tracing risks leaving us blind to outbreaks among the elderly and the poorest: those most in danger from this disease.

We risk repeating the tragedy currently taking place in care homes. It is by no means guaranteed everyone will download the app: one draft paper from the London School of Hygiene and Tropical Medicine estimates that only 53 per cent of the population will download the app – more than 32 million downloads in just a few months and, between now and July, nearly 700,000 downloads per day.

All of these strategies rely on increasing testing as well. If only 6,000 people, with 45 contacts each, are infected every day, we will need a capacity of 276,000 tests just to keep up. And this does not include regular testing for contact tracers, NHS and care workers, nor the Pillar 4 surveillance testing to track the disease at large in the country.

These tests will have to be delivered with the help of the private sector. In my former role as chair of the Public Administration and Constitutional Affairs committee, we looked at precisely this capacity for the government to deliver major projects and contract work to private companies. This is not the time for timidity: the government must be unafraid to use its power to make strenuous and clear efforts to harness the private sector in order to deliver.

None of these challenges is insurmountable: organising millions of downloads, hundreds of thousands of daily tests and tens of thousands of contact tracers can be done. The Government must be prepared to move quickly and, just as the Prime Minister did on Sunday, trust the public with the truth, complexity and ambiguity of all the ‘ifs’ in present policy, to maintain their consent. The one thing we cannot do is to pretend that the ‘R’ number will go away or can be ignored, as the renewed lockdowns in Seoul, Singapore and North Rhine-Westphalia are beginning to demonstrate.