Dominic Cummings has taken a brutal swipe at Boris Johnson’s girlfriend Carrie Symonds for “going crackers” over a “trivial story” at the height of the coronavirus pandemic.

At a critical time in March when the government was considering the first lockdown, The Prime Minister’s former aide claimed Donald Trump and Mr Johnson’s girlfriend created distractions.

Mr Cummings was giving evidence to the Commons health and science committees with No 10 braced for explosive claims about the Prime Minister’s handling of the pandemic.

According to Mr Cummings, the then-US president Donald Trump wanted the UK to join America in a bombing campaign in Iraq.

He also claims Ms Symonds was “going crackers” over a story from The Times regarding the couple’s dog, Dilyn, and demanded the N010 press office dealt with it.

He said: "Part of the building was arguing about whether we were going to bomb Iraq, part was arguing about whether we were going to quarantine or not, and the Prime Minister's girlfriend was going crackers about something completely trivial".

Dominic Cummings said he had “mounting panic” about the response to coronavirus in early March last year.

He said he was pushing for the Government to announce that individuals should stay at home if they had symptoms and households should quarantine on March 11, but he said there was “push back” from others who felt the advice could be delayed for another week.

“There was push back from within the system against advising the following day, i.e the 12th, to say stay at home if you’ve got symptoms,” he told MPs.

“And me and others were realising at this point the system is basically delaying announcing all of these things because there’s not a proper plan in place.”

He added: “As far as I could tell from Sage, and as far as the minutes show, the fundamental assumption remained we can’t do lockdown, we can’t do suppression, because it just means a second peak.”

Dominic Cummings also said he is “completely baffled” as to why No 10 has tried to deny that herd immunity was the official plan early last year.

The former chief aide to the Prime Minister told the Commons committee: “It’s not that people were thinking this is a good thing and we actively want it, it’s that it’s a complete inevitability and the only real question it’s one of timing, it’s either one of herd immunity by September or it’s herd immunity by January after a second peak. That was the assumption up until Friday March 13.”

He said that Health Secretary Matt Hancock was “completely wrong” on March 15 to say herd immunity was not part of the plan.

“That was the plan. I’m completely baffled as to why No 10 has tried to deny that because that was the official plan,” Mr Cummings said.