LONDON (AP) — Boris Johnson, the former British prime minister, struggled to come to grips with much of the science during the coronavirus pandemic, his chief scientific advisor said Monday.

In keenly awaited testimony to the country’s public inquiry into the COVID-19 pandemic, Patrick Vallance said he and others faced repeated problems getting Johnson to understand the science.

“I think I’m right in saying that the prime minister gave up science at 15," he said. “I think he’d be the first to admit it wasn’t his forte and that he struggled with the concepts and we did need to repeat them — often.”

In extracts from his diary that were relayed to the inquiry, Vallance said Johnson was “bamboozled” by the graphs and data and that watching him “get his head round stats is awful."

Vallance said Johnson's struggles were not unique and said many leaders around Europe had problems in understanding the scientific evidence and advice, especially in the first stages of the pandemic in early 2020.

“I would also say that the meeting that sticks in my mind was with fellow advisers from across Europe, when one of them — and I won’t say which country – declared that the leader of that country had enormous problems with exponential curves, and the telephone call burst into laughter, because it was true in every country,” he said.

“So I do not think that there was necessarily a unique inability to grasp some of these concepts with the prime minister at the time, but it was hard work sometimes to try and make sure that he had understood what a particular graph or piece of data was saying.”

The U.K. has one of the highest COVID-19 death tolls in Europe, with the virus recorded as a cause of death for more than 232,000 people.

Johnson, who was forced to step down as prime minister in September 2022 following revelations of rule-breaking parties at his Downing Street residence during the pandemic, is due to address the inquiry before Christmas.

The probe, led by retired Judge Heather Hallett, is expected to take three years to complete. Johnson agreed in late 2021 to hold a public inquiry after heavy pressure from bereaved families, who have hit out at the evidence emerging about his actions.