In 1918, Parkes was appointed an editor of ''Jane's Fighting Ships
, a post he held till 1935. At first, he was joint-editor with Maurice Prendergast, and from 1922 to 1930 with Francis McMurtrie. From 1930 to 1935 he was sole editor. The last edition of Jane's Fighting Ships'' he was involved with was the December 1934 issue. Parkes' book
Ships of the Royal Navy was first published by
Sampson Low, Marston & Company in 1922. It would be reprinted in seven revised editions the next 15 years, and had a change of title to
Ships of the Royal Navies (British Commonwealth of Nations) in 1935. In 1929, Sampson Low published the first edition of Parkes' book ''The World's Warships''. Also from 1935 to 1940, he was being widely quoted in American newspapers and the
United States Congress, warning about Japanese naval development and expansion, pointing out, that is where the focus of world powers should lie. He was an advocate for western navies' future needs for smaller, faster vessels, aircraft carriers, and torpedo delivery. Between the wars, he set up a specialist practice in Hans Crescent,
Knightsbridge, acting between 1920 and 1924 as a
neurological adviser to the
Ministry of Pensions. All the while he worked on ''Janes's Fighting Ships'' in the evenings from his home in
Sunbury-on-Thames, with his wife Natalie acting as his assistant. They moved to
Ringwood,
Hampshire in 1943, and he continued in general practice there, for a short time working at
Fordingbridge Hospital. Oscar Parkes was one of the early members of the
World Ship Society, founded by Michael Crowdy in 1946, as the Ships News Club, a way of distributing shipping information to correspondents. What started with some 50 correspondents quickly developed into 200–300 within a year. It is an international society devoted to maritime and naval history. in 1915 by Parkes Aside from his role as editor of ''Jane's Fighting Ships
, Parkes contributed many naval articles to the Navy League Magazine'', the
Society for Nautical Research's academic journal for maritime history, the ''
Mariner's Mirror'', and other journals. As a physician, Parkes wrote medical articles on the control of disease, rheumatism, electro-therapy,
ozone therapy, and other subjects. == Later life ==