Dominic Cummings may have committed “a minor breach” of lockdown rules when he drove to Barnard Castle but will face no further action, Durham Constabulary said on Thursday.
The force said Mr Cummings has been informed of the decision not to take retrospective action in relation to his trip to Barnard Castle on Easter Sunday.
Mr Cummings said he went on a “short drive” to the tourist attraction on April 12 because his eyesight had been affected by the disease and his wife did not want to risk the long drive back to London.
Prime Minister Boris Johnson is continuing to stand by Mr Cummings despite the Durham Police findings.
A Number 10 spokesman said: “The police have made clear they are taking no action against Mr Cummings over his self-isolation and that going to Durham did not breach the regulations.
“The Prime Minister has said he believes Mr Cummings behaved reasonably and legally given all the circumstances, and he regards this issue as closed.”
Durham Constabulary said in a statement: “On April 12 2020, Mr Cummings drove approximately 26 miles from his father’s property to Barnard Castle with his wife and son.
“He stated on May 25 2020 that the purpose of this drive was to test his resilience to drive to London the following day, including whether his eyesight was sufficiently recovered, his period of self-isolation having ended.
“Durham Constabulary have examined the circumstances surrounding the journey to Barnard Castle (including ANPR, witness evidence and a review of Mr Cummings’ press conference on May 25 2020) and have concluded that there might have been a minor breach of the regulations that would have warranted police intervention. Durham Constabulary view this as minor because there was no apparent breach of social distancing.
“Had a Durham Constabulary police officer stopped Mr Cummings driving to or from Barnard Castle, the officer would have spoken to him, and, having established the facts, likely advised Mr Cummings to return to the address in Durham, providing advice on the dangers of travelling during the pandemic crisis.
“Had this advice been accepted by Mr Cummings, no enforcement action would have been taken,” the statement added.
Durham Constabulary also said there was “insufficient evidence” to support reports that Mr Cummings was in Durham on April 19.
A witness said Mr Cummings was seen looking at bluebells in woods near Houghall close to his family’s home.
But Mr Cummings says the story is false, claiming that photos and data on his phone prove he was in London.