Peter Duncan was born on 22 April 1882 at Liverpool, England. At the age of 18, he followed in his father’s footsteps by joining the Royal Navy and became a stoker. Whilst serving on HMS Hecla in late 1908, he gained his Engineer’s Writer certificate. This qualification allowed him to look after the administration of the engineering department.
By the time Duncan was loaned to the Royal Australian Navy (RAN) in November 1912, he had gained the rank of petty officer stoker. He became a crew member of HMAS Australia and was on board when the ship entered Sydney Harbour with the rest of HM Australian Fleet on 4 October 1913. By November 1913, Duncan was acting chief stoker and in December he had qualified as Engineer’s Yeoman of Stores.

At the outbreak of the First World War, HMAS Australia operated in local waters to deter the German Asiatic Squadron and took part in operations to seize German colonies in the Pacific. HMAS Australia was ordered to England in late 1914 and arrived there on 28 January 1915, before spending the rest of the war in the North Sea, conducting sweeps, patrols, and convoy escort duties. On board HMAS Australia, Duncan’s efficient capable manner and organisational and mechanical skills endeared him to his crew mates and he became a well-respected member of the crew.

After the end of the war, Duncan was discharged from the RAN in October 1920, but entered the reserves for five years. From 1935 to 1941 he was storeman for the Department of Defence’s RAN Armament Depot at Spectacle Island, Sydney and was later employed as a munitions worker. Peter Duncan died in Sydney on 7 March 1955.