Robert Peston: Chronic uncertainty over who is allowed to go to work and why there aren't enough coronavirus tests

There are still potentially lethal ambiguities in the government's coronavirus advice about who should go to work - such is the judgement of leading employers, to whom I've spoken.

The fundamental question is whether businesses that are not doing work considered of national importance, but which involve employees working cheek by jowl in sweaty conditions, should cease operating.

The head of one of the UK's largest companies is absolutely clear to me that the government has given a signal that such operations should send staff home and switch off the machines.

But a distraught mother of an employee of an Midland steelworks forwarded me a message from the firm boss saying they were staying open - because they are not in prime minister's list of sectors ordered to shut - and "we therefore all need to be there".

The "all" in this case include many men in their forties, fifties and sixties, who are thought to be particularly at risk from Covid-19.

The government has moved into a phase of banning people from being in groups, pretty much anywhere but the home.

Coronavirus tests exist, but there aren't enough of them. Credit: PA

So what is it about the steelworks or any other business requiring close physical contact that isn't engaged in work vital to the health and security of the nation that justifies it staying open?

In China, you'll recall, pretty much all manufacturing ceased in Hubei during the lockdown.

One answer is that some economic activity has to be sustained in the UK, or an economic contraction and reduction in our prosperity that is already likely to be more acute even than any phase of the Great Depression could be so extreme as to set back recovery for months and years.

But of course this entire dilemma highlights yet again what many are describing as the scandal of how slow the government has been to increase the UK's Covid-19 testing capacity.

The biggest advantage of being able to mass test is that if someone falls ill at the factory, he or she could be tested, those in contact with the ill person could be tested too, and a rational decision could be taken on whether the factory could continue operating.

Absent that ability, the safety first principle argues for mass closures of all services and manufacturing that requires any kind of human contact, with devastating economic consequences.

In other words, whatever the short term financial costs of ramping up testing, the long term economic damage of not having sufficient testing capacity outweighs it by a hundred or thousand times.

The former health secretary Jeremy Hunt pointed out to me this morning that this weekend the UK was still carrying out only five-and-a-half thousand tests per day - nowhere near the PM's recently announced targets of 10,000 a day and 25,000 a day.

This is woefully inadequate if the Chief Scientific Adviser Sir Patrick Vallance was correct when he told MPs a few days ago that there were probably 1000 infections in the population for every death - because it would suggest the number of cases here (most unidentified) is already in the hundreds of thousands.

Another measure of the testing shortfall is that the UK is carrying out about 40,000 tests a week, less than a quarter of the tests being made in Germany - where, as it happens, the mortality rate from Covid-19 is a fraction of the mortality rate here (presumably because the tests allow the hospital system to identify vulnerable sufferers before they enter the most acute phase of the illness).

The priority of course is for us to pull together to get through this crisis as best we can.

So this may not be the optimal time for recriminations and the search to identify those who - for reasons best known to them - did not identify several weeks ago the importance of testing and therefore did not ramp up the UK's inadequate capacity.

But for what it's worth, even 12 days ago when I highlighted the government's plan to go for so-called "herd immunity" by managing the rate of spread of the infection - as opposed to the volte-face just over a week ago to suppression of the virus - it would have been rational to accompany that policy with a system for real-time monitoring of who actually has it.

Let's come back to the who, why and what, when we have time and space to breathe and think.

But in the meantime the imperative for journalists like me is to test that when the prime minister announces - as he did last week - that he had made a priority of moving to mass testing, that these are not just words and something actually changes.