Welcome to the forums! The above members are quite correct, your watch appears to be a quite uncommon "Stealth" watch issued to the SOE during WW2. These watches were designed to have no defining characteristics, or charecteristics at all. Very few of these watches survived, due to many being misplaced in action. If it's not running, it could be an issue, as few jewellers are qualified nowadays to work on these models, as most of the expertise and documentation surrounding them has sadly been lost to time.