hi
if you do a google search for , WW2 BRITISH ARMY GSTP POCKET WATCH BY CYMA there is one displayed for sale , it appears that the number on the back is the serial number for the particular watch , chances are if it was a british gov issue I doubt you will find who it was issued to but you may strike lucky , also by doing another google search it appears there are no british outlets for cyma watches and the main company offices are in Switzerland , anyway do a google search and see what comes up there are numerous sites regarding cyma including forum sites as well they may be able to shed some light on the watch as no doubt there are experts out there who can help .
yours trevor
ps does the back of the watch have the arrow marking for all things military stamped above the serial number ?