I have a hypothesis that G (MercersTroop) Battery had two Troops (A & B ) while K Battery had three (D, E and F). This is because I have assumed that when the new Junior Battery founded in Nov 1940 CC Bty took the next available spare letters (C, and H) these must have been unused - implying that G bty had only two troops. The 12 gun three troop battery was adopted as a way to expand the field artillery while minimising the demands on scarce radios and trained junior commanders. A 12 gun battery allowed for a 50% increase in the number of guns without needing 50% more battery commanders, COs and their HQs and wireless sets. There were disadvantages of this structure which was abandoned within 18 months. The RHA may have resisted a dilution of their elite standards. I am not sure how thoroughly the decision not to expand the RHA Batteries might have been documented, as the discussion might have been more likely over a pink gin in Woolwich than at a desk in Whitehall. It does not help that we are dealing with D,E&F Troops of K Battery RHA and G (Mercers Troop) Filed Battery RHA and whether Wixley was a GPO in G Battery or might have been in the GPO vehicle of E Troop... However, the reason why both numbered, field and lettered RHA, Field batteries had lettered troops and gun subs was to avoid confusion on the gun position. The actions that took place on a gun were defined in gun drill books for each member of the gun detachment, whose roles were numbered, e.g. the no 1 was the detachment commander the No3 the layer. Any practical period of drill will include the commands "Tell Off" which requires each member of the detachment to yell out their number. (Usually followed by the command "change round" and repeated to see if Gunners could remember a different number.) To keep it simple on the gun position, guns and vehicles are are letters while gunners are numbers. The Royal Regiment of Artillery lettered its guns sub sections, grouped these into sections called "left, centre and right" in each lettered troop. So an order for "No1s to the Gun Position Officer" will result in the detachment commanders doubling across the position and cannot be misinterpreted as the order for A Sub to be manhandled out of action, even by the most simple minded gun bunny. Is there any evidence that Wixley received his MC?