Cummings tells an extraordinary story.
He says on the morning of 12 March, the "national security people came in" and said "Trump wants us to join a bombing campaign in the Middle East tonight".
He says this "totally derailed" meetings on coronavirus and household quarantines.
He says, at the same time, "the prime minister's girlfriend was going completely crackers" over having the No 10 press office deal with stories in the press about the Downing Street dog.
Part of the building was talking about bombing Iraq, part was talking about household restrictions, and "the prime minister's girlfriend was going completely crackers about something trivial," he states.