Our governments never declare five tests without having made their minds up in advance.  So it was with Gordon Brown’s five tests for joining the Euro.  They were designed to ensure that we never would.  The purpose of these ones is the opposite.

Three of them are legerdemain.  Who will decide whether the rate of infection “is decreasing to manageable levels”?  (Test three.) Who will “need to be confident” that the supply of testing and PPE will be able to meet future demand?  (Test four.)  Why, none other than Ministers, who will make decisions with an eye to the polls.  They will ultimately be guided not by “the science” but by “the politics”.

True, it would be awkward for them to claim that there has been “a sustained and consistent fall” in daily death numbers (not “rates”, as Dominic Raab said, since we can’t be sure how many people have the Coronavirus) if the Government’s scientific advisers were unwilling to back them up. (Test Two.)

But the pass has already been sold on that one.  Chris Whitty said on Wednesday that the peak is “flattening out”.  Ministers would not have included this test as one of the five were they not confident that the advisers will soon be willing to signal a thumbs-up.

When? As this site reported yesterday, Boris Johnson is up and about texting people from Chequers. The hope in Downing Street is that he will be back at work after the first May Bank Holiday on May 8.  He would then be able to look at a report from the joint Number Ten/Cabinet Office unit examining proposals from the departments about how to lift the lockdown.

Test One (“we must protect the NHS’s ability to cope” and Test Five (“we need to be confident that any adjustments to the current measures will not risk a second peak of infections that overwhelm the NHS”) are in essence the same. Again, they ultimately require a political decision.

The Department of Health can be expected to be very cautious about that fifth test.  But it gives the Prime Minister enough wiggle room to say, during the days after the bank holiday, that they have been met if the shutdown is eased off gradually.

In other words, Johnson will seek to keep ahead of public opinion – which he is doing triumphantly so far: polls show overwhelming support for the Government’s position.  The art for him is to not to be caught out by a sudden shift in mood as closures, job losses and destitution reach a critical mass.  We asked yesterday whether that might be early June – a quarter of the year in from the original wave of entrenchment in March.

The announcement in early May of a partial end to the lockdown might successfully juggle appeasing those who want it ended, satisfying those who believe that it is still essential, and keeping the Health Department and the Treasury on the same page.

Above all, it would continue to meet the Government’s primary aim: ensuring that the NHS can indeed cope with any relaxation of social distancing.  We make no complaint whatsoever about all these being political decisions.  That’s of their essence.

The biggest fly in this ointment is the assumption that the Prime Minister will be back to his usual bouncing self by after the May Bank Holiday.  If he isn’t, he will have some serious thinking to do about whether Dominic Raab should be empowered to step up to the next level.

Yesterday, the latter could simply have said that the lockdown will last for another three weeks – and nothing much else.  That he didn’t confirms that the Government is preparing its way out.