When war broke out, in September 1939, Vernon was classed as an ‘enemy alien’ due to his German birth. His classification as ‘Category C’ – the level indicating the lowest level of threat to Britain – meant he had no curb on personal freedoms. But, from June 1940, the government declared that all male enemy aliens between 16 and 60 were to be interned. Vernon was arrested on 17th July 1940. He would be held in three camps during his internment, in Shropshire, Liverpool and the Isle of Man.