Boris Johnson has stuck by his top aide Dominic Cummings, saying he “followed the instincts of every father and every parent” and “I do not mark him down for that”.
The prime minister insisted his special adviser had “acted responsibly and legally and with integrity” after facing criticism for travelling from London to Durham during lockdown.
Mr Cummings was called into 10 Downing Street earlier on Sunday following reports he went into self-isolation at his family’s farm 260 miles away with his child and wife, who had COVID-19 symptoms.
A growing number of Tory MPs called for him to be sacked for the journey that came while Britons were being told to “stay at home” to stop the virus spreading at the end of March.
But at the daily Downing Street coronavirus briefing, Mr Johnson said after “extensive face-to-face conversations” with Mr Cummings, he concluded the former Vote Leave boss “had no alternative” but to make the trip.
He added that Mr Cummings had been “travelling to find the right kind of childcare, at the moment when both he and his wife were about to be incapacitated by coronavirus”.
Mr Johnson acknowledged the damage the allegations had the potential to do.
He said the “big question” being asked was “is this government asking you – the people, the public – to do one thing, while senior people here in government do something else?”
“Have we been asking you to make sacrifices, to obey social distancing – stay at home – while some people have been basically flouting those rules and endangering lives?”
The prime minister explained his conversations with his top adviser over the weekend were “because I take this matter so seriously”.
Questions still loom over Mr Cummings’ movements after a witness claimed to have spotted him 30 miles from his family’s farm walking by the River Tees near Barnard Castle on 12 April, during the period he was believed to be self-isolating.
Robin Lees, a retired chemistry teacher, told Sky News he spotted Mr Cummings on that occasion and wrote down a “distinctive” number plate.
Mr Cummings was also reportedly spotted by another member of public in Houghall Woods near Durham home on 19 April.
Mr Johnson did not directly dispute the two other allegations about Mr Cummings when they were put to him by a journalist at the news conference.
The prime minister said he had “looked at them carefully” and was “content that at all times throughout his period in isolation… he behaved responsibly and correctly and with a view to defeating the virus”.
A statement by Durham Police, who say they spoke to Mr Cummings’ family, also conflicts with Downing Street’s claim the family was not contacted by officers.
Labour leader Sir Keir Starmer, who has called for an inquiry, said Sunday’s briefing was “a test of the prime minister and he has failed it”.
“It is an insult to sacrifices made by the British people that Boris Johnson has chosen to take no action against Dominic Cummings,” he said in a statement.
“The public will be forgiven for thinking there is one rule for the prime minister’s closest adviser and another for the British people.
“The prime minister’s actions have undermined confidence in his own public health message at this crucial time.
“Millions were watching for answers and they got nothing.”
One Tory MP – David Warbuton – said after the news conference that he was “unconvinced” by the prime minister’s defence.
A former Downing Street adviser until December 2019, Tim Montgomerie, also told Sky News he was “incredibly disappointed” and criticised a “terrible failure on the part of government”, adding sacking Mr Cummings would risk the whole administration falling apart like a game of Jenga.
Number 10 is “like a ship with a massive hole in the bottom, leaking water at a rapid rate” and Mr Johnson has “just put a bigger hole in the boat”, he reflected.
A tweet from the official UK civil service account posted just after the news conference said: “Arrogant and offensive. Can you imagine having to work with these truth twisters?”
It was later deleted and a government spokesperson said the “unauthorised tweet” is being “investigated”.
Analysis by Joe Pike, political correspondent
This was a big decision for Boris Johnson, a bold call to wholeheartedly back his chief adviser.
The prime minister argued that Dominic Cummings “acted responsibly and legally” and “followed the instincts of every father”.
Yet Mr Johnson looked uncomfortable at today’s news conference and avoided answering key questions from journalists, including claims that Mr Cummings made a day trip from Durham to Barnard Castle at the height of the lockdown.
It makes one thing abundantly clear: Mr Cummings is too valuable for Boris Johnson to lose at such a critical time for the government and the country.
Today’s news conference was painful, but it seems sacking him would have been a far bigger wrench for the PM.
As one minister told me earlier: “Nobody could have got us through the last year like [Dominic Cummings] did”, in particular in making Brexit happen.
The danger for Boris Johnson is that this episode has consequences far beyond Westminster: and threatens the public’s willingness to follow the government’s public health advice.