Police in Durham have concluded that Dominic Cummings did break lockdown rules when he drove to Barnard Castle, it has been reported.
The Telegraph is reporting they have learnt that is the result of an investigation by police in Durham.
It was concluded there was a minor breach that did not warrant any further action.
But a Government spokesman has confirmed that Boris Johnson's most senior adviser won't be sacked for the breach.
A Number 10 spokesman said: "The Prime Minister has said he believes Mr Cummings behaved reasonably and legally given all the circumstances and he regards this issue as closed".
Mr Cummings claimed he made the trip on Easter Sunday, with his wife and four-year-old son, to check he was fit to drive after suffering coronavirus-related eyesight problems.
He made the revelations as he read a statement from the rose garden of 10 Downing Street on Monday.
But he denied visiting the castle itself or walking around the town and says he only got out of his car to walk to the river bank.
"We made the short drive to see if I could drive safely," he said. "We didn't visit the castle or walk around the town."
There have been mounting calls for Mr Cummings to resign after it was revealed he had made a 260-mile trip from London to Durham during lockdown to his parents' estate and then the second trip to Barnard Castle.
