Dominic Cummings has the “full support” of the Prime Minister after details emerged that he travelled 250 miles to County Durham during the lockdown.

Boris Johnson had come under pressure to sack his top aide after it was revealed he drove his wife and child from their London home to a family property in the North East after his spouse developed coronavirus-related symptoms.

Transport Secretary Grant Shapps, speaking at the daily Downing Street Covid-19 briefing, said: “I can tell you the PM provides Mr Cummings with his full support.”

Number 10 had already offered the former Vote Leave campaign co-ordinator its backing when putting out a statement on Saturday, stating that Mr Cummings’ actions “were in line with coronavirus guidelines”.

But Mr Shapps’ latest comments are an indication that the PM is sticking by the controversial figure, who he credited with helping secure him his landslide election victory in December.

Mr Shapps said he did not know whether Mr Johnson was aware that his chief adviser was isolating in the North East, only that the “PM knew that he was unwell and that he was in lockdown”.

The SNP has called for the Conservative Party leader to sack Mr Cummings, with the party, along with Labour and the Liberal Democrats, having written to Cabinet Secretary Sir Mark Sedwill demanding an inquiry into what happened.

A snap poll by YouGov found that 68% of Britons think Mr Cummings broke coronavirus rules by taking his family to Durham, while 52% think he should resign.

The survey of 3,707 adults, carried out on Saturday, showed just 28% think he should stay on, with 20% on the fence.

Meanwhile, the poll revealed Conservative voters were split over whether he should retain his position, with 41% of those who responded saying he should quit while 43% want him to remain as senior adviser to Mr Johnson.

According to a joint investigation by the Guardian and Daily Mirror, Mr Cummings was spotted twice in the vicinity of his parents’ home in Country Durham over the course of almost a week, between March 31 and April 5.

Downing Street had previously confirmed that Mr Cummings had started displaying coronavirus symptoms “over the weekend” of March 28-29.

Number 10, in its statement on Saturday, confirmed the 48-year-old had not yet started displaying Covid-19 symptoms when he drove to Durham, but did so in the “high likelihood” he would contract it and need childcare for his four-year-old son.

Deputy chief medical officer Dr Jenny Harries said travelling during the lockdown could be justified if there was an “extreme risk to life”.

Refusing to comment on Mr Cummings’ specific case, Dr Harries told the press conference: “In relation to the advice to the public, it’s absolutely clear that public health guidance is, if you’re symptomatic you stay at home, take yourself out of society as quickly as you can with your family and stay there, unless there is extreme risk to life.”

Mr Cummings, speaking to reporters outside his London home on Saturday, said he had acted “reasonably and legally”.

When a reporter suggested to him outside his London home that the trip to Durham did not look good, he replied: “Who cares about good looks?

“It’s a question of doing the right thing. It’s not about what you guys think.”

Durham Constabulary said in a statement on Friday that officers contacted the owners of a property on March 31, more than a week after the lockdown had been imposed by the PM, when they were made aware of reports that an individual had travelled from London.

Downing Street denies police spoke with members of Mr Cummings’ family in relation to his journey.

In a statement, a No 10 spokesman said: “Owing to his wife being infected with suspected coronavirus and the high likelihood that he would himself become unwell, it was essential for Dominic Cummings to ensure his young child could be properly cared for.

“His sister and nieces had volunteered to help so he went to a house near to but separate from his extended family in case their help was needed.

His actions were in line with coronavirus guidelines. Mr Cummings believes he behaved reasonably and legally

“His sister shopped for the family and left everything outside.

“At no stage was he or his family spoken to by the police about this matter, as is being reported.

“His actions were in line with coronavirus guidelines. Mr Cummings believes he behaved reasonably and legally.”

Speaking on Friday, a spokesman for Durham Constabulary said: “On Tuesday, March 31, our officers were made aware of reports that an individual had travelled from London to Durham and was present at an address in the city.

“Officers made contact with the owners of that address, who confirmed that the individual in question was present and was self-isolating in part of the house.

“In line with national policing guidance, officers explained to the family the arrangements around self-isolation guidelines and reiterated the appropriate advice around essential travel.”

The force declined to update its statement after the Downing St comment.

But Durham Police and Crime Commissioner Steve White said officers “acted appropriately”.

Mr White, a former head of the Police Federation in England and Wales, said it was “most unwise” for the Downing Street adviser to have travelled when “known to be infected”.

During the press briefing, Mr Shapps was pressed on why there was a discrepancy between Downing St and the police’s accounts.

Mr Shapps said: “I am not sure where the confusion in that comes in, but we have got it in black and white in his statement.”

As well as Mr Shapps, fellow Cabinet ministers have rallied behind Mr Cummings, including Cabinet Office Minister Michael Gove, Health Secretary Matt Hancock, Attorney General Suella Braverman and Culture Secretary Oliver Dowden.

Mr Hancock tweeted: “I know how ill coronavirus makes you. It was entirely right for Dom Cummings to find childcare for his toddler, when both he and his wife were getting ill.”

Ms Braverman said “protecting one’s family is what any good parent does” and claimed it was “wholly inappropriate to politicise” the situation.

The defence of Mr Cummings, who formerly worked for Mr Gove, comes despite resignations previously being welcomed by senior Tories in the case of similar examples of public officials ignoring lockdown guidelines.

When Professor Neil Ferguson, the epidemiologist whose modelling prompted the lockdown, quit as a member of the Scientific Advisory Group for Emergencies (Sage) for flouting distancing rules when he was visited by his girlfriend, Health Secretary Matt Hancock said he was “speechless”.

But Mr Shapps argued Mr Cummings’ circumstances differed from Prof Ferugson and Dr Catherine Calderwood, Scotland’s chief medical officer who was forced to quit after it was discovered she disobeyed lockdown rules to twice visit her second home.

The former Tory chairman said: “I would draw this distinction: this wasn’t sort of visiting a holiday home or going to visit someone.

“This was to stay put for 14 days, to remain in isolation to get over what I understand was quite a significant bout of illness from coronavirus, and then to be able to return to London only when well.”