It has dominated his premiership, put him into intensive care, provoked a bitter row and rebellion with his parliamentary party and could – depending on the result of the Met Police investigation – ultimately cost Boris Johnson his job.

So you could imagine the prime minister’s sense of relief on Monday when he announced the ending of COVID restrictions.

It offered the embattled Mr Johnson a rare moment of approbation from some of his fiercest backbench critics in the Commons and an occasion to display a bit of his trademark boosterism from a politician who in recent weeks has worn a permanently furrowed brow.

This was, said the PM, the “time to get our confidence back” as he spoke of the ending restrictions as a “moment of pride”.

Public urged to take personal responsibility

From this Thursday, the legal requirement to self-isolate following a positive COVID-19 test will be scrapped and free testing for the general public will end on 1 April. Financial support for those isolating will also end on 24 March.

Read more: What will ‘living with COVID’ mean when coronavirus restrictions end in England?

The PM urged the public to take personal responsibility, as the obvious questions about how they can afford to do it if they have neither sick pay for isolation or access to tests rained down.

But if the PM sought to use this moment to project confidence, his scientists chose to sound caution at the COVID news conference.

Sir Patrick Vallance warned the pandemic was not over, that there could be more severe strains.

Sir Chris Whitty cautioned that winters could still be tricky as he urged the public to carry on using sensible precautions, such as wearing masks in enclosed spaces, testing if meeting elderly people and washing hands.

The different tones were significant because the prime minister’s decision to end not just restrictions now, but support around sick pay and free testing in a few weeks, is as much a political decision as a public health one.

Read more: Next variant ‘could be more severe’ with future winters ‘tricky’, govt advisers say

Advisers advise, ministers decide but in this particular instance, the prime minister has been under sustained pressure from his own party and cabinet to end COVID laws at a time when his political authority is at an all time low. It raises obvious questions about his motivations in making these announcements today.

Gung ho politicians and cautious scientists

He knows it and was at pains at the news conference on Monday to tackle that head on. When I asked Sir Patrick and Sir Chris whether they were feeling more anxious than confident about the ending of restrictions it was the PM who answered the question that wasn’t directed at him.

“On the anxiety point, I don’t want you to think there is some division between the gung ho politicians and the cautious, anxious scientists,” said Mr Johnson.

“We have to face the fact, there could, likely will be, another variant that will cause us trouble. But I believe, thanks to what we have done, particularly with investment in vaccines, we’ll be in a far better position to tackle that new variant when it comes.”

And as for the scientists, Professor Chris Whitty said he would describe himself as cautious while Sir Patrick said the “one thing this virus has taught you is not to be cocky. We need to go very carefully, monitor carefully, and be prepared to react”.

Enough to save the PM?

Mr Johnson will be glad to put controversial COVID laws behind him – for now at least, although in the short-term he must still be acutely anxious over whether the police will conclude he broke the very rules he wrote into law.

For weeks his MPs have been muttering that a PM who broke the law must surely face a confidence vote and even have to resign.

But the last few days may have changed that calculation as events at home are overtaken by the very real prospect of a European war. Just as COVID recedes, this is a prime minister, and a continent, now facing a new and grim global challenge.