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The Guardian first approached Downing Street for a comment in April after being told by a neighbour of Cummings's parents that they had seen him at the Durham property on 5 April.
When Boris Johnson introduced the United Kingdom lockdown he gave "a very simple instruction - you must stay at home".
The source explained that Mr Cummings travelled from London with his wife, who was also ill with coronavirus symptoms, to his parents' home near Durham, so that his parents could help to care for their young child.
This was despite Boris Johnson having declared a lockdown in England days beforehand on March 23rd.
The rules stated that people would only be allowed to leave the house for limited purposes including shopping for basics, one form of exercise a day, travelling to and from work, but only where absolutely necessary, and medical needs.
The BBC reported that an anonymous source close to Cummings had claimed that a "small number of people in No 10 knew that Cummings had gone to Durham".
Laura Kuenssberg tweeted the news this morning.
"On Tuesday, March 31, our officers were made aware of reports that an individual had traveled from London to Durham and was present at an address in the city", a statement from Durham Police said.
He has served as Senior Advisor to the Prime Minister since Boris Johnson's arrival in Downing Street in July 2019.
On top of pressure over Mr Cummings, ministers were facing backlash from the aviation and travel sector following the publication of more details of plans to subject worldwide travellers to spot checks and £1,000 fines if they fail to self-isolate for 14 days after arriving in the UK.
The call was echoed by the Scottish National Party's Westminster leader Ian Blackford, calling Mr Cummings's position "completely untenable".
Ed Davey, acting leader of the Liberal Democrats, said that if Cummings had broken the rules, "he will have to resign".
"What I find interesting.is that (according to some reports) members of Downing Street knew about this so, first and foremost, Boris Johnson has serious questions to answer over what now appears to be a cover-up".
The trip took place at the end of March, just days after the Prime Minister announced strict lockdown measures, including banning all non-essential travel, and giving the police powers to impose fines on anyone breaking lockdown rules.
Dorset's police and crime commissioner, Martyn Underhill, said such a high-profile breach of the rules by Cummings would make it more hard for police to enforce the lockdown.
The appointment of the abrasive former campaign director was controversial, given he was found to be in contempt of Parliament earlier in the year for refusing to give evidence to MPs investigating misinformation.