The mechanical general service watch was initially manufactured for CWC by the Hamilton factory, and is identical to the preceding watches from Hamilton that had been issued from 1973 until 1975. These watches had been based on an updated Defence Standard that had been published in 1971 picturing the tonneau-shaped case, and had in turn replaced the Smiths watch which had been issued from 1967 to 1970,
Around 24,000 CWC watches were issued by the British Army in 1976, 1977, 1979 and 1980 – of which 10,000 were issued in 1976 – with smaller numbers issued by the RAF in 1979 and the Royal Navy from 1977 to 1979. This preponderance of W10-marked examples is what gives the watch its name.
Batches and known issue numbers are:
1976 W10: 2002 to 11968
1977 W10: 277 to 5154
1977 0552: 015 to 079
1978 0552: 079 to 250
1979 W10: 2222 to 9364
1979 0552: 1016 to 1277 and 9272 to 9645
1979 6BB: 033 to 2427
1980 W10: 0023 to 1993
There are two styles of 0552 marked watches - the 1977 batch has the NSN marked 0552-523-8290 all in one line, whilst the 1978 and 1979 batches have 0552 on one line, and 523-8290 on the line below. Pictures of some of the 0552 watches can be found here.
The dial design is identical across all these watches; the CWC logo and a circled T above the hands, and the broad arrow below the hands, luminous indices and a luminous triangle at 12 o'clock, SWISS below the 6 index, and white numerals. The hour and minute hands are tritium lume-filled and the seconds hand is white. The movement is the ETA2750 with hacking (ability to stop the seconds hand for precision time setting), and the case is a monocoque (one piece) construction.
In addition to the British military-issued watches, two other variants have been seen, issued by overseas militaries; a watch with an O in place of the Service code issued by the Sultan of Oman's Land Forces in 1979 and 1980, with known serial number ranges of 078/79 to 477/79 and 104/80 to 229/80; and a watch with a shortened NSN and KK either side of the broad arrow issued in 1977 with known issue numbers of 035 to 174, the issuing authority of which is currently unknown.