Downing Street said Dominic Cummings believed he “behaved reasonably and legally” when travelling from his London home to Country Durham during the lockdown.
Reports emerged on Friday saying the senior aide to Prime Minister Boris Johnson had travelled to his parents’ home in Durham in breach of the UK Government’s own lockdown rules.
Mr Cummings started suffering from coronavirus at the end of March and self-isolated with his wife, journalist Mary Wakefield, and young son for 14 days.
Downing Street said he was in his London home – and afterwards his wife wrote about “emerging from quarantine” into the London lockdown.
But a joint investigation by the Mirror and the Guardian suggests that Mr Cummings was in fact in the North of England.
A Number 10 spokesman said on Saturday morning: “Owing to his wife being infected with suspected coronavirus and the high likelihood that he would himself become unwell, it was essential for Dominic Cummings to ensure his young child could be properly cared for.
“His sister and nieces had volunteered to help so he went to a house near to but separate from his extended family in case their help was needed.
“His sister shopped for the family and left everything outside.
“At no stage was he or his family spoken to by the police about this matter, as is being reported.
“His actions were in line with coronavirus guidelines. Mr Cummings believes he behaved reasonably and legally.”
Minister for the Cabinet Office Michael Gove has spoken out on behalf of Mr Cummings, tweeting: “Caring for your wife and child is not a crime.”
The Mirror reported that police confirmed they had visited an individual at an address in the city who they had learned had travelled to Durham from London during the lockdown to self-isolate.