North Wiltshire MP James Gray says that unless Dominic Cummings can justify what he did, he should give up his role as a Government adviser.

Mr Cummings travelled to County Durham in March to self-isolate with his family – apparently because he feared that he and his wife would be left unable to care for their son – while official guidelines warned against long-distance journeys.

Further reports also suggested he took a second trip to the North East in April, having already returned to London following his recovery from Covid-19 – a disease which has seen more than 36,000 people in the UK die after contracting it.

Several Conservative backbenchers have joined calls from opposition parties for Mr Cummings to quit or be sacked, amid warnings that his actions have “undermined” efforts to fight coronavirus.

However, the prime minister, Boris Johnson, said he could “not mark down” Mr Cummings for the way he acted, and told the Downing Street press conference on Sunday that, following “extensive” talks with his aide, he concluded “he followed the instincts of every father and every parent”.

He said Mr Cummings had “acted responsibly, legally and with integrity”.

In a letter to his constituents, James Gray said: "None of us yet know the details of what Mr Cummings did, nor why. It may be that more will emerge in the coming days to justify (or to condemn) his behaviour.

"But for now I believe that at a time when thanks to his advice we are all going through lockdown, our personal circumstances very often being a great deal worse than his, it most certainly does look like a double standard to apparently ignore his own advice.

"That is without question the perception throughout the land.

"I therefore do think that unless and until he can justify what he did, he should face the consequences of it and give up his role as a Government adviser.

"Having him continuing at the heart of Government undermines our credibility and the strength of our message.

"Over the next few difficult weeks and months we need the full confidence of the people if they are to agree to the steps which will be necessary both for their lives and for their livelihoods.

"And for that to happen they need to have full confidence in the Government which is asking them to do it.

"So it is my view that Mr Cummings should at very least step back from Government with no further delay."