I have not found any evidence that Standard Motor Co. was ever involved with making airplane engines, although they did build Royal Aircraft Factory and Sopwith planes under license during WW1 using other people’s engines, Hispano-Suiza and RAF mostly. They were building six cylinder car engines as early as 1905.
If the draftsmen at Standard were anything like those at my lab, the guy who first drew the crankshaft in 1905 would have put the flywheel flange on the left side of his paper and dimensioned all the crank pins from there, numbering them 1-6 left to right. The machinists, assemblers and service people would naturally follow that lead.
Jaguar did not continue the back-to-front numbering with the V12; cylinders 1A and 1B are in the front.