Walwyn joined the Royal Navy in 1893, spending two years training at the Dartmouth Britannia Royal Naval College before joining the battleship with the rank of midshipman. He served as acting sub-lieutenant from December 1898, and was confirmed in this rank on 7 February 1900, when he was posted to the pre-dreadnought battleship, serving in the Mediterranean Fleet. Later that year he was promoted to lieutenant on 15 December 1900, seeing action in the Second Boer War. In 1904 Walwyn was posted to, the Naval Gunnery School at Whale Island, Hampshire, as a Gunnery Lieutenant. After a year he went on to serve as Gunnery Lieutenant aboard the cruiser, and the battleships and, until promoted to commander on 1 July 1912. Walwyn was then appointed Assistant to the Director of Naval Ordnance at the Admiralty, remaining in that post through the first year of the First World War, finally returning to sea duty in 1915 as 1st Lieutenant of. There he saw action in the Battle of Jutland on 31 May – 1 June 1916, and was subsequently awarded the Distinguished Service Order on 15 September. He was promoted to captain on 31 December 1916, and in June 1917 was awarded the Order of St. Stanislas, 2nd Class by Russia. Walwyn was appointed commander of the first class protected cruiser on 17 January 1919, and, from 29 April 1920, he commanded the destroyer leader, also serving as Captain, 2nd Destroyer Flotilla. From 1922 he served as Captain, 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 in March 1926, until she started a refit later that year. Soon after, he took command of, remaining with her until March 1927. On 29 February 1928 he was promoted to rear admiral. He was appointed a Companion of the Order of the Bath on 4 June 1928. 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, and on 2 January 1933 was made a Knight Commander of the Order of the Star of India. 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.
From 1936 Walwyn served as Governor of Newfoundland and chairman of the Commission of Government. On 6 June 1939 he was appointed a Knight Commander of the Order of St. Michael and St. George. During the Second World War he was active in encouraging Newfoundlanders to join the war effort. In 1946, he retired to Maiden Newton, Dorset, where he died in 1957.
Family
In recognition of her public and philanthropic work for the community in Newfoundland, his wife, Lady Eileen Mary Walwyn, 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. Their son was Rear-Admiral James Humphrey Walwyn, R.N., C.B. O.B.E..
