Hi Bruce,
Thanks for the reply, I knew that Guy had reverse engineered one of the machines (T.D. 1035) and had based this around some of the A.Std rollers found in south africa (I believe). I have a copy of many of the A.Std items but this new numbering system was something I came across digging through the AP’s. I hadn’t come across this before and was wondering if it was particular to the manufacturer of the tools rather than the design authority (Hawker) or the RAF stores reference (the 26B number)? Sometimes some of the original drawings from a manufacturer still exist and I have even found some in local libraries when the companies archives were donated.