In 1902 Walwyn was posted to Excellent, the Naval Gunnery School at Whale Island, Hampshire, to train as a Gunnery Lieutenant. Upon qualifying he was appointed to the school's staff for six months. From 1905 he served as Gunnery Lieutenant in the cruiser Drake and the battleships Superb and Neptune. He also spent 18 months on the staff of the Inspector of Target Practice at the Admiralty. He was promoted to the rank of commander on 1 July 1912.[4]
Walwyn was appointed commander of the first class protected cruiserGibraltar on 17 January 1919,[8] and, from 29 April 1920, he commanded the destroyer leaderSpenser, also serving as Captain (D), 2nd Destroyer Flotilla.[9] From 1922 he served as Captain (D), 7th Destroyer Flotilla, and as Senior Officer, Mediterranean Destroyers, before returning to the Admiralty in 1924 to serve as Director of the Gunnery Division. He took command of the battleship Queen Elizabeth in March 1926, until she started a refit later that year. Soon after, he took command of Valiant, remaining with her until March 1927.[10]
The same year Walwyn was appointed Flag Officer Commanding and Director of the Royal Indian Marine, receiving promotion to vice admiral on 1 November 1932,[13] and on 2 January 1933 was made a Knight Commander of the Order of the Star of India (KCSI).[14] He oversaw the change of the Royal Indian Marine to the Royal Indian Navy in October 1934, of which he was the first Flag Officer Commanding, but retired in November 1934 after only a month. He was placed on the Retired List on 15 December 1934.[citation needed]
In recognition of her public and philanthropic work for the community in Newfoundland, his wife, Lady Eileen Mary Walwyn (1883–1973), the daughter of Major General Turner van Straubenzee, CB and Florinda Harriette van Straubenzee, was created a Dame Commander of the Order of the British Empire on 1 January 1947.[16] Their son was Rear-Admiral James Humphrey Walwyn, R.N., C.B. (1964) O.B.E. (1944).[17]
