[Chock]

There is a possibility that the M relates to a name, but it is a remote one. Most RAF squadrons used letters A-F for A Flight, G-N for B Flight and M-R for C Flight, pointing to it being either a C Flight or possibly a B Flight machine. Letters after that sequence were often assigned to spare/back up aircraft or some such, but the system wasn't always rigidly stuck to, since aircraft were flown in and out from squadrons to repair depots quite regularly, and they did swap around a bit as maintenance routines mixed things up. Sometimes the CO's would use unusual letters as a kind of perk too, which could lead to out of sequence lettering in flights, but these were more often letters such as W or Z or whatever, or sometimes A, since it has leader connotations. But unlike in the German air service, where initials were common, it was kind of frowned upon to be too ostentatious in such matters in the somewhat stuffy British military persona.

Even in WW2 when RAF Squadron leaders were allowed to use personal letter codes, it was officially discouraged since it it was thought that it might single them out for special attention from the enemy, which is an unlikely prospect in a swirling dogfight, but the thought nevertheless prevailed. However, the general opinion from many pilots was that when they had fought their way up through promotions, they were damn well going to have the perk of a personal marking.

Al