There are 2 versions of the red book but with identical identification. (Air publication No 1726 Vol I, Part II Book No. 101/NC.3.A.)
The first version is basically the standard up to late 1944. The second version is almost identical but describes most likely the changes for S5161.
It refers to the late, simplified, lighting system with the push button in the instrument panel and the switch under the saddle.
There are no references to Aircleaners in either version.
Air publication would be more like an RAF thing but the 101/NC codes are more like REME. Not sure who was in charge here.
The NC code is identical to the codes used in the VAOS listings for Norton parts so REME appears most likely.
The size of the red books clearly indicates it is not to be used by the MC rider themselfs, only by workshops or company Fitter.
More likley to be R.A.O.C., I think. The "NC" code was in use for spare parts under the VAOS system and they were responsible for supplying vehicles, parts and literature.
The RAF codes appeared after The Ministry of Supply took over joint purchasing for the War Office and The Air Ministry. They presumably insisted on shared publications.
