The opinions on the origin of the IG/AIG cap distinctions vary slightly. According to Guy, Lt.Col J.R. “A history of gunnery Wing Royal School of Artillery”, from the formation of the amalgamated “School of Gunnery” in 1920 at Larkhill, the IGs wore a red cap band to indicate that they had passed the “long staff course”.
However, according to James, N.D.G., “Gunners at Larkhill. A history of the Royal School of Artillery” Henley-on-Thames: Gresham Books and the Royal Artillery Institution, 1939 is based on as earlier article appearing in the “Gunner” in May and June 1956 the red-hatband had originated at the School of Gunnery at durymess? in about 1906. “All officers had white jackets without rank distinctions, but Instructors wore there blue peaked forage caps with the white linen cover over the crown and has continued up to the 1914-18 war for IGs at Schools of Gunnery but not in Commands or at defended ports. With the abolition of full-dress the red cap-band was presumably transferred to the service dress cap.
That AIGs should wear a white hat cover was decided at a meeting presided over by the CIG in 1926, students were instructed to wear white armbands although this was later discontinued. Since 1939, however, safety officers during practice have worn white armbands.