Ronald Milne was born in Wanstead, London on 8 February 1903, the eldest son of Alexander George and Emily Isabel Milne. He joined the Royal Navy as a Boy Artificer on 9 January 1919 and on completion of his Apprenticeship, he was drafted to the battleship HMS BENBOW on 23 September 1923 and served in that ship until 12 October 1925. Ronald Milne joined the destroyer HMS WESSEX from 22 December 1925 to 21 May 1926 and then joined submarines on 5 June 1926 at HMS DOLPHIN for the Submarine Course.

Drafts to HMS L19, HMS L23 and HMS H28 followed, and then Ronald Milne was sent to Hong Kong and joined HMS OLYMPUS from 1 April 1934 to 31 March 1936. he was promoted to Warrant Engineer on 1 October 1938 and appointed to HMS DOLPHIN for submarine training on 2 January 1939. On completion of his training, he was appointed to HMS L26 as Engineering Officer on 3 July 1939.

On 15 October 1939 he was appointed to the HMS TRITON as Engineering Officer. On 6 December 1940, Ronald Milne was lost when TRITON was sunk with all hands.

Ronald Milne was the husband of Elsa Gertrude Milne (née Cowtan), and he is commemorated on the Portsmouth Naval Memorial on Panel 37, Column 2.