A training film made, I think in either late 1945 or early 1946 entitled "Royal Navy at War - Naval Bombardment-Part 1" can be found at:
https://www.youtube.com/watch?v=t2qIU5SH_s8
At approx. 3 mins 30 secs a Bombardment Liaison Officer can be seen at work - in BD with standard titles ROYAL ARTILLERY and RA AoS strips - and between the two, unusually, a
square format Combined Operations sign. Forward to approx. 5 mins 50 secs - an Army Officer - possibly an Air Liaison Officer or Carrier Borne Ground Liaison Officer (CBGLO colloquially known to the RN as Seaballs) wearing on one arm a small patch which might be the white letter A on a navy blue or black square - A for Air? I'll now continue watching the film - Seafires in action in the spotting role come up next. Mike