Grant Shapps, the transport secretary, said he did not think the journey would have been “high on (his) agenda”.
He categorically denied Mr Cummings went back to Durham after returning to London in mid-April.
But he failed to rule out that Mr Cummings may have made a sightseeing trip 30 miles from his family’s home on Easter Sunday.
Mr Shapps told the Sophy Ridge show he was sure Mr Cummings obeyed social distancing rules and added: "I don't have all the times and dates for you but I understand he will have travelled up there towards the end of March and stayed there, remained there for 14 days, didn't leave the property and isolation, as per the rules and guidance.”
He said: "You'll appreciate I wasn't with them so I can't tell you exactly what that journey was like, but what I do know is that Dominic Cummings - I saw a clip yesterday of him asking journalists to be spaced two metres apart, so I know he is a stickler for those rules about what to do to make sure you are following the two-metre rule and the like, so I'm sure that they took all the necessary precautions."