Claude Choules was born in Pershore, Worcestershire, on 3 March 1901 and raised in nearby Wyre Piddle. The son of Harry and Madeline (née Winn), Claude was one of seven children, although two died in early childhood. The surviving siblings were Douglas, Leslie, Phyllis, and Gwendoline. His mother left home when Claude was five, returning to the stage as an actress, and he and his older brothers were raised by his father. His older sister Phyllis lived with the family of a paternal uncle, while his younger sister Gwendoline was adopted by the family of a paternal aunt. Both Claude and his older brothers went to Pershore National Boys' School (see national school), though Douglas (born 1893) and Leslie (born 1894) emigrated to Western Australia in 1911.
Choules was 13 at the start of World War I, and the family received letters from Leslie and Douglas who had joined the Australian Imperial Force and landed at Anzac Cove and fought during the Gallipoli Campaign. Choules was able to leave school when he turned 14, at which point he attempted to enlist in the army as a bugler boy but was rejected as too young. Choules' father then arranged for him to train to join the navy instead, and in April 1915, at age 14, he joined the nautical training ship TS Mercury.
This training ship was moored on the River Hamble, near Southampton, Hampshire, and had a dormitory ship called HMS President that had previously been HMS Gannet. The commander of the Mercury training site was the cricketer C. B. Fry, and Choules' time there included trips to Netley Hospital as part of the Mercury's dancing team. The examinations taken by Choules following his training on the Mercury qualified him to attend the Advanced Class on the naval training ship HMS Impregnable situated at the Devonport naval base in Plymouth. Choules transferred there on 10 October 1916, for what was to be the final stage of his training before joining the Royal Navy's Grand Fleet.
On 20 October 1917, Choules joined the battleship HMS Revenge, which was the flagship of the First Battle Squadron and stationed at Scapa Flow in the Orkney Islands. While serving aboard it, Choules saw action against a German zeppelin, and witnessed the surrender of the German Imperial Navy at the Firth of Forth in 1918, ten days after the Armistice, as well as witnessing the scuttling of the German fleet in Scapa Flow.
In 1926, along with 11 other Royal Navy senior sailors, Choules travelled to Australia on loan as an instructor at Flinders Naval Depot. He travelled on the SS Diogenes on a 6-week voyage from London to Melbourne, and it was on this voyage that he met his future wife Ethel Wildgoose who was travelling to Australia to carry out work for the Victoria League. Choules decided to transfer permanently to the Royal Australian Navy (RAN) after sampling and agreeing with the Australian way of life. In fact, he was only two days younger than the RAN, which was established on 1 March 1901.
He took his discharge from the RAN in 1931, but remained in the reserves and rejoined the RAN in 1932 as a Chief Petty Officer Torpedo and Anti Submarine Instructor. He never returned to England after leaving.
During the Second World War, Choules was the Acting Torpedo Officer based at Fremantle, Western Australia, and also served as the Chief Demolition Officer on the western side of the Australian continent. He was tasked with sabotaging Fremantle harbours and related oil storage tanks in the event of a Japanese invasion. Choules was also responsible for dealing with the first German mine to wash up on Australian soil during the war, near Esperance, Western Australia.
Choules remained in the RAN after the Second World War and transferred to the Naval Dockyard Police (NDP) to allow him to remain in service until 1956, as retirement from the RAN for ratings in those days was at age 50, while personnel could serve until 55 years old in the NDP.