LONDON (AP) — Boris Johnson, the former British prime minister, struggled to understand much of the science during the coronavirus pandemic, his chief scientific advisor Patrick Vallance said Monday. Vallance spoke of the challenges he faced trying to communicate complex scientific concepts to Johnson and how he often had to repeat them for him to grasp.

Vallance testified in front of the UK’s public inquiry into COVID-19 pandemic and relayed that Johnson was “bamboozled” by graphs and data, and that it was difficult for him to understand statistics. Vallance also pointed out that many other leaders around Europe also struggled with understanding scientific evidence and advice in the early stages of the pandemic.

The UK has one of the highest COVID-19 death tolls in Europe, with over 232,000 deaths recorded as a result of the virus. Johnson is expected to address the inquiry before Christmas, after heavy pressure from bereaved families who have criticized his actions during the pandemic. The probe is led by retired Judge Heather Hallett and is expected to take three years to complete.