In June 1946, tens of thousands of curious Britons flocked to a former air raid shelter on New Oxford Street. Just over a year had passed since the Second World War had ended in Europe, leaving in its wake a devastated continent. The public had come to get a glimpse of the people who had started it all. They had come to see an exhibition called Germany Under Control.

As they moved from room to room, visitors took in the menace that seemed to radiate from the large bronze eagle that had once adorned Adolf Hitler’s Chancellery. There were also more mundane objects, such as saucepans made from German army helmets and military equipment that had been turned into agricultural tools.…