Those who could not work from home were advised to speak to their employers about a return to their workplace. People were allowed to exercise an unlimited amount in a day, and the previous ban on people sitting on a bench outside was lifted.

Rules governing social distancing were enforced, with initial fines for those breaching them raised to £100 from £60 for a first offence, eventually rising to £3,200 for serial offenders.

All hospitality settings were closed, except for takeaway food, and people could not meet more than one other person outside their household on their own.

Britons urged to ‘limit contact with other people’ at the time

Oliver Dowden, the then Culture Secretary, said during press conference on May 20, 2020 – the day of the reported party – that “normal life as we have known it is still a long way off” and that Britons should be “limiting contact with other people [and] keeping distance if you do go out – two metres apart where possible”.

“If everyone stays alert and follows the rules, we can control coronavirus by keeping the ‘R’ down and reducing the number of infections,” he said.

But a former standards chief said that “technically speaking” Mr Johnson had not misled Parliament with comments he made at the end of last year about separate reports of parties.

Dr Hannah White, who previously ran the committee for standards on public life in the Cabinet Office deputy director of the Institute for Government think-tank, told Radio 4 it would be difficult for Mr Johnson to deny any knowledge of what took place.

“I think it’s pretty surprising that this happened at all, that [Martin Reynolds] decided to put it on record by sending an email seems even more surprising,” she told the Today programme.  

“He’s the Principal Private Secretary as you say, one of the key officials working for the Prime Minister, and I think it’s true to say that it’s extremely unlikely he could have invited 100 people to a party in the Downing Street garden without the assent of the Prime Minister.”

‘Increasingly difficult’for PM to claim he didn’t know

On whether the Prime Minister approved the party, Dr White added: “I think he would have had to have done, and also there are witnesses saying he was there. 

“So it’s becoming increasingly difficult for him to claim he didn’t know about this particular breach of lockdown rules. He’s said that, and he’s entirely correct to say, there’s an inquiry under way.”