DOMINIC Cummings is facing calls to resign from his role as Boris Johnson’s chief adviser after it was claimed he broke lockdown rules by travelling 260 miles from his London home.

The police are said to have intervened after receiving a tip-off that the controversial aide had travelled to his family home in County Durham to self-isolate, despite the Prime Minister having declared a lockdown in England days beforehand.

At the same time as the UK Government was instructing people to remain home - with fines in place for those contravening the rules - Mr Cummings, according to a joint investigation by the Guardian and the Mirror, decided to escape the UK capital.

The 48-year-old is alleged to have been present at his family home when police from Durham Constabulary turned up on March 31, following a call from someone reporting they had seen Mr Cummings in the area.

READ MORE: Coronavirus: The high-profile figures who have breached lockdown restrictions 

Durham police confirmed officers had spoken to the owners of an address in the city after reports a person had travelled there from London.

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 guidelines around self-isolation and reiterated the appropriate advice around essential travel."

Downing Street had previously confirmed Mr Cummings had started displaying coronavirus symptoms "over the weekend" of March 28 and 29.

The same day as police spoke with members of Mr Cummings' family, Mr Johnson was being admitted to hospital with coronavirus, where he would later require treatment in intensive care.

According to the two newspapers, the PM’s chief adviser was spotted a second time at the property on April 5.

Tonight, Ian Blackford, the SNP leader at Westminster, said the aide's position was "completely untenable".

"He must resign or be sacked," declared the Highland MP.

Mr Blackford also tweeted: "This is a key test of leadership for Boris Johnson. People must have confidence that the Tory Government is following its own rules, not being investigated by the police for breaking them."

Sir Ed Davey, acting leader of the Liberal Democrats, said: "If Dominic Cummings has broken the lockdown guidelines, he will have to resign, it is as simple as that."

Labour, meanwhile, said No 10 needed to issue a "very swift explanation" about what went on.

A party spokesman said: "If accurate, the Prime Minister's chief adviser appears to have breached the lockdown rules. The Government's guidance was very clear: stay at home and no non-essential travel.

"The British people do not expect there to be one rule for them and another rule for Dominic Cummings."

Labour MPs Angela Eagle and Stella Creasy also took to social media with the Wallasey MP tweeting: “One law for them another for the rest'" while her colleague, who represents Walthamstow in London, posted: "So, we can now take children from a household where people have tested positive to stay with the likely over 70s? Missed that exemption in the guidance."

However, friends of Mr Cummings insisted he was going nowhere.

One said: "He isn't remotely bothered by this story; it's more fake news from the Guardian. There is zero chance of him resigning."

Cabinet ministers have previously supported the decision of those involved in the Government's response to Covid-19 resigning after disobeying the lockdown.

Earlier this month, Professor Neil Ferguson, the leading epidemiologist, whose modelling with Imperial College London prompted the lockdown, quit as a member of the Government’s science advisory body SAGE, after it emerged he was visited by his married lover.

Last month, Catherine Calderwood, Scotland’s Chief Medical Officer, quit after it was discovered she had made two trips to her second home in Fife.

Mr Cummings, formerly one of the key strategists behind the Vote Leave campaign, wrote about his experience of isolating with his wife, Mary Wakefield, in the Spectator magazine.

He wrote that "at the end of March and for the first two weeks of April I was ill, so we were both shut in together".

Ms Wakefield, also writing in the Spectator, which she is an editor for, said she became ill with Covid-19 symptoms before her husband did.

"I felt breathless, sometimes achy, but Dom couldn't get out of bed," she said.

READ MORE: Coronavirus: Dominic Cummings self-isolating after displaying symptoms

"Day in, day out for ten days he lay doggo with a high fever and spasms that made the muscles lump and twitch in his legs. He could breathe, but only in a limited, shallow way."

No 10 has been approached for comment.

Downing Street had regularly refused to confirm where Mr Cummings was self-isolating after news broke that he was ill, possibly with coronavirus.

Mr Cummings has since returned to work at No 10.