Hi Nimrod
I can't give you a definitive answer, but the mechanicals from CWC & Hamilton were produced in the 1970's. My Hamilton is a 1976 issue, and my CWC a 1979. I don't remember seeing any with a 1980 or above issue date. There was a 1 jewelled MWC watch also, although there is some debate as to who these were issued to. Ziggy mentions in his book that they were issued to forces stationed in Germany.
The earliest quartz G10 I own is a 1982 CWC with the thicker case. My Precista is from the same period. I know of no other quartz G10 manufacturers apart from the recent Pulsars.
Cheers
Foggy