In early 1935, Cummins volunteered to join the Royal Air Force (RAF). He enlisted at the Air Crew Reception Centre in Regent's Park, London, where both serving members of the RAF and new recruits were assessed for training. Cummins initially trained as a rigger, tasked with undertaking flight checks on aircraft. His superiors considered Cummins to be an ambitious individual, although he was not popular among many of his fellow servicemen, who resented his boastful attitude and claims to hail from nobility. These false claims to hail from an aristocratic background earned Cummins the derogatory nickname "the Duke". In May 1936, he became acquainted with Marjorie Stevens, the secretary of a West End theatre producer. The two first met at an Empire Air Day air show in the village of Henlow. Following a seven month courtship, the couple married at the Paddington Register Office on 28 December. The couple had no children.