From the Edwyn Allen Magazine 1952 - note the FSR badge was retained by the officers and not the cadets.
THE C.C.F. BADGE.
The disappearance of black paint from the cap badge this term removes the last link with the First Surrey Rifles, the Regiment whose uniform is so familiar a memory to former members of the O.T.C. Major E. C. Eayrs, who commanded the Corps from 1932 to 1937, contributes a note which will be of interest to many A.O.B.s and to the present C.C.F. The following passage is a valuable addition to Corps. history:
," When the Alleyn's School Cadet Corps was established in 1915, the unit was affiliated to the 21st County of London Regiment (First Surrey Rifles) and consequently wore the badges of the Regiment.
, In 1923 the Cadet Corps became a contingent of the O.T.C. (Junior Division).
It is customary, for such contingents to wear badges associated with the school, but in this particular instance, at the request of the School authority was granted by the officer Commanding the F.S.R., Lt.-Col. A. Hutchence, M.C., T.D., for the school unit to continue the use of the Regimental badge, and this authority received the approval of the War Office. Hence all the Officers of the O.T.C. wore the same badges as the Officers of the F.S.R. and all ranks had black buttons."
This continued until 1936 when the contingent began to be administered by the Brigade of Guards, and the school coat of arms, in black, was adopted as the capbadge. Battle-dress began to replace the old tunics and puttees at Rossall in 1944.
https://www.alleyns.org.uk/uploaded/...1952_-_OCR.pdf