Boris Johnson’s attempts to get Britain back on track after coronavirus threaten to be overshadowed by the continued fallout over Dominic Cummings’ lockdown trip.

The Prime Minister chose to front the daily Downing Street Covid-19 briefing to publicly back Mr Cummings on Sunday, saying he had “acted responsibly, legally and with integrity” by driving 260 miles to County Durham to isolate and that “any parent would frankly understand what he did”.

But Tory backbenchers tore into Mr Johnson over his handling of the row, while scientists claimed the defence of Mr Cummings’ interpretation of the lockdown rules undermined efforts to curb the spread of the deadly virus.

The storm over Mr Cummings’ actions overshadowed Mr Johnson’s latest signal that the lockdown is easing as the Prime Minister confirmed the phased reopening of England’s primary schools will commence on June 1.

He is also, according to Government sources, set to reveal plans to ease restrictions for certain sectors of the economy – with the changes expected to signal the reopening of some non-essential shops – when the Cabinet meets on Monday.

But the drama incited by news of Mr Cummings’ lockdown travels – made on fatherly “instinct” to ensure care was available for his son, according to Mr Johnson – will spill over into bank holiday as senior Tories continued to criticise the decision to keep the aide on.

Former minister Paul Maynard said: “It is a classic case of ‘do as I say, not as I do’ – and it is not as if he was unfamiliar with guidance he himself helped draw up.

“It seems to me to be utterly indefensible and his position wholly untenable.”

Senior Tory MP Simon Hoare, who had earlier called for Mr Cummings to go, later lamented Mr Johnson’s press conference, telling the Daily Mail: “The PM’s performance posed more questions than it answered. Any residual hope that this might die away in the next 24 hours is lost.”

Somerton and Frome MP David Warburton said he was “unconvinced” by the PM’s defence of Mr Cummings, while Tory grandee Lord Heseltine said it was “very difficult to believe there isn’t a substance” in the allegations about Mr Cumming’s movements.

“I think these unanswered questions are now on the agenda,” he told the BBC, “and I don’t think that this anxiety about the Government’s position will end until we know the whole story.”

Another Tory MP, Jason McCartney, said while it was important for people to show compassion during the crisis, Mr Cummings had to go because the “perceived hypocrisy of the rule makers potentially threatens the success of any future measures” under a second wave of the coronavirus.

Social psychologist Professor Stephen Reicher, one of the scientists on the Scientific Pandemic Influenza Group on Behaviours (SPI-B) – a subgroup of the Scientific Advisory Group for Emergencies (Sage), which is advising ministers through the crisis – said Mr Johnson had “trashed” their advice.

Meanwhile, the PM also came in for stinging criticism from bishops, while Mr Cummings is likely to face further questioning after he was reported to Durham Constabulary over alleged sightings of him across the county during the lockdown period.

Church of England bishops accused the PM of treating people “as mugs” and with “no respect” after he opted to stick by his chief aide.

The Rt Revd Nick Baines, Bishop of Leeds, tweeted: “The question now is: do we accept being lied to, patronised and treated by a PM as mugs?”

Mr Cummings travelled to County Durham in March to self-isolate with his family while official guidelines warned against long-distance journeys, apparently because he feared that he and his wife would be left unable to care for their son if both incapacitated by coronavirus symptoms.

Further reports also suggested the 48-year-old took a second trip to the North East in April, having already returned to London following his recovery from Covid-19 – a disease which has seen more than 45,000 people in the UK die after contracting it, according to the latest available data.

And, in developments which will pile more pressure on the Government, an alleged eyewitness, who says he saw Mr Cummings on a third occasion on April 12, told the Mirror he had reported the controversial figure to Durham Constabulary for a suspected breach of lockdown.

Robin Lees, a retired teacher, thinks he spotted Mr Cummings out in Barnard Castle in County Durham on Easter Sunday, at a time the 71-year-old reckons he should have still been quarantined, seeing as police said his father had confirmed he was isolating in the region as of March 31.

Transport Secretary Grant Shapps was asked about the alleged April 12 outing during a media round and said, if it took place, the visit “would have been outside the 14-day period” for self-isolation.

It comes as Councillor Amanda Hopgood, the leader of the Liberal Democrat opposition on Durham County Council, said she had written to Durham police’s Chief Constable Jo Farrell after being made aware of a number of sightings of the PM’s senior aide in the area in April and May.

Coronavirus police
Police officers leave after having knocked on the door of Prime Minister Boris Johnson’s senior aide Dominic Cummings at his north London home (Victoria Jones/PA)

Rallying against the tide of condemnation levelled at their son, Mr Cummings’ parents, Morag and Robert, defended him in an interview with the New Statesman.

His mother said the family had been grieving after her brother – Lord Justice Laws – died on April 5 after contracting Covid-19 while ill in hospital.

She said: “I have no other comment to make other than to say that my brother died on Palm Sunday, and the press has not been cognisant of that fact, either from Dominic’s point of view or from mine.”

The day his uncle died and his boss was admitted to hospital for his coronavirus symptoms, an unnamed neighbour told the Mirror and the Guardian they saw Mr Cummings in the garden of his parents’ home as Abba’s Dancing Queen was playing loudly.

His father added that he was “disgusted” at the way the press had treated his son during the coverage.

Police attended Mr Cummings’ London home on Sunday afternoon after it was “reported that a large crowd of people were outside the address”.

Scotland Yard would not confirm who had called officers.

Footage posted on social media also showed Mr Cummings was heckled by a crowd of onlookers as he returned to his house in the capital after the Downing Street press conference.

Those gathered called him a “hypocrite” and shouted “resign”.