26er: I'm pretty sure it's the guys initials, but just covering the bases in case it meant something elsewhere!
I think the guy must have been in Coastal Command as I have pretty extensive Bomber Command sites searched without success. I have asked a Coastal Command guru if he has any info, similarly 10 OTU (Codes were JL@A etc....)
No trace so far in Flight Archives where I would have expected to find promotion details etc.. Still looking, but all help appreciated!