A TORY minister has said Dominic Cummings’ departure is now "only a matter of time" as Boris Johnson’s top aide was seen going into Number 10.

Pressure is now mounting on Boris Johnson from within the Conservative party as well as from the SNP, Labour and public health experts to sack his senior adviser who left his London home with his wife and child and travelled 260 miles to Durham during lockdown despite the stay at home rules.

ITV's Robert Peston reported a minister had told him it was “only a matter of time” Cummings would be asked to leave.

The political editor also quoted a minister saying: "What is very frustrating is that Cummings is only an adviser, and yet he is being protected in a way that would never happen to a minister. Jenrick [the housing and communities secretary] almost had to resign for doing something much less serious."

The journalist also went on to quote a government member who said: "We are expecting the police to enforce the rules. But if we are seen to be protecting one of our own, our authority isn't what it should be."

Former minister Caroline Nokes wrote on Twitter: "My inbox is rammed with very angry constituents and I do not blame them."

Tory MP and arch-Brexiteer Steve Baker, speaking on the Sophy Ridge On Sunday programme, also said it was time for Cummings to go.

"If he doesn't resign, we'll just keep burning through Boris's political capital at a rate we can ill afford in the midst of this crisis," he said.

"It is very clear that Dominic travelled when everybody else understood Dominic's slogans to mean 'stay at home, protect the NHS and save lives'.

"And I think mums and dads who very much care about their children and who have been forgoing the childcare of their extended family will wonder why he has been allowed to do this.

"I really just don't see, as we approach the Prime Minister (appearing) at the liaison committee on Wednesday, how this is going to go away unless Dominic goes."

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Baker, MP for Wycombe, said: "I'm afraid I just think this is the end of the road. I objected to Dominic going into Number 10 on the day Boris became PM, my colleagues weren't with me. I think it's worked out badly, as it was bound to do.

"Dominic's tactics are out of place and he should go, and this moment has revealed that really he has ended up not abiding by the spirit at least of the slogans which he has enforced on the rest of the country."

Devi Sridhar, professor of global public health at Edinburgh University, also called for Cummings to resign.

Speaking on the Sophy Ridge show, she said: "He undermined the core public health message which was to stay home, to make sure that children are not left with elderly relatives and also going from an area that was ahead of the country - London - to an area that was a bit behind, north-east England.

"North-east England is now one of the hardest hit parts of the country.

"So the clear thing is, yes, he needs to resign, but we also need to move on and bring focus to the key issues facing the UK.

"The UK now has close to 60,000 excess deaths, one of the worst death rates per capita in the world, we are in a lockdown.

"We don't have a good way out of this lockdown because there is no testing and tracing infrastructure to let us safely lift the lockdown, and we have a lot of people suffering because of a lack of clear strategy of how we are going to move forward and get out of the deep hole that we are in."

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Conservative MP Simon Hoare tweeted: "With the damage Mr Cummings is doing to the Government's reputation he must consider his position.

"Lockdown has had its challenges for everyone. It's his cavalier 'I don't care; I'm cleverer than you' tone that infuriates people.

"He is now wounding the PM/Govt & I don't like that."

Damian Collins, the Conservative MP for Folkestone and Hythe, said in a tweet: "Dominic Cummings has a track record of believing that the rules don't apply to him and treating the scrutiny that should come to anyone in a position of authority with contempt.

"The government would be better without him."

Transport Secretary Grant Shapps said that Cummings stayed put after travelling to Durham after fresh claims the adviser made a second visit to Durham during lockdown after returning to London from the first trip.

He said the latest allegations that Cummings returned to Durham and was spotted on April 19 were untrue.

He told the Sophy Ridge programme: "I think there are more stories today that I'm seeing that he travelled backwards and forwards, accusations he then went back up to Durham again further times - I understand it is completely untrue.

"When he came back to London, which was on April 14 I see, he has remained in London since and hasn't been back to Durham.

"There are all kinds of things that are being said here that are completely untrue.

"The basic story is actually pretty straightforward. Husband and wife were ill, they hunker down, they look after their four-year-old and they don't move until they are better.

"And coming back down to London afterwards, they would have been travelling for essential work which is always allowed as well."

Cummings remained silent as he was asked whether he would be resigning as he entered Number 10 this afternoon.

Yesterday he said he didn’t care if his lockdown trip from London to Durham looked good or not.

The senior governmental advisor emerged from his home on Saturday morning and answered reporters' questions about the journey.

When asked if it looked good, he said: “Who cares about good looks?

"It’s a question of doing the right thing. It’s not about what you guys think.”