Lord Sedwill said he would have “expected” work to continue during a 10-day gap in mid-February in which Boris Johnson received no notes or emails related to coronavirus.
Asked about the drop-off in work on pandemic preparation, he said: “I would have expected it to continue, yes.”
He also conceded that by the end of February levels of alarm inside the Government, given official warnings about the imminent crisis, “should have been” higher.
“It’s hard looking back to recall quite how extraordinary were the measures we later took. They were unconscionable at the time. And, therefore, I think your point about this instinctive human reaction is true.
“I think it was also the case at the end of February the number of cases in the UK was – on the data available – still very small.
“One can understand how non-experts not familiar with exponential movement might have misunderstood the pace at which the disease was moving.”
He acknowledged that Mr Johnson might have shared that optimism bias. “He is an optimistic person,” he told the hearing.