It's not really a medal; it's more like a badge. The same goes for the QGJM; I got one just for being in uniform at the time even though I couldn't quite do up the top button on my trousers (they seemed to have shrunk)!
On the other hand the QSJM, in '77, because it was rationed, tended to be handed out on merit. I was allocated one medal for my flight of more than 100 RAF and RN tradespersons. I awarded it to a Junior Technician who had just failed his promex to Cpl, for the fourth time!
However, in the preceding 12 months he had developed a servicing procedure (SP) on his own initiative, which reduced the aborted Spey starts on the RAF and RN F4 fleets by more than 50%.