In World War II he was a soldier in the Pioneer Corps. In November 1940, while on leave, he married Mary Ross (1913–2006), who had been an amateur actress in the Swansea Little Theatre. He and Mary would have two children – a son and a daughter (Hilly, born 1954). Janes was posted to Egypt, where he worked for two and a half years in a prisoner-of-war camp. There he learnt Swahili and Italian, and made friendships with some of the Italian prisoners which he would maintain in after years.