If I may add on just for the Yanks in the audience.
Commnwealth services operated slightly differently than AAF in that their pilots were not always officers.It was common to find a Sergeant at the controls and a Lieutenant manning the tail gun--just the opposite of what you would find in the US air services.
In British-Canadian parlance, a Pilot Officer is a progression of RANK not an indication of specialty.A P/O could very well BE a pilot, but a Bomb Aimer or Navigator or a gunner or even the officer in charge of the Mess Hall.It is just a progression of rank.
The subheading of his specialty is Wireless Operator/Air Gunner.The non-PC abbreviation for this was WOG--but more commonly WAG.His brevet (wing) would have the letters WAG in the center of the wreath.
Dave Berry www.PathfinderHistoricalConsultants.com