Terry Andrews here has been compiling information on this matter for a number of years and hopefully sometime down the track will compile it all into something coherent. Other than going through hundreds of older threads on this forum and over on Eddie's TZUK and others, there are no real reference books or literature on the subject. Konrad Knirim wrote a companion book on non-German military issued watches which covers the UK divers etc but no hard information like you are seeking. CWC still exists lock, stock and smoking barrel but obviously now owned for a number of years by Silvermans. You could always wander over to Silvermans and pick their brains and Ray Mellor the former CWC owner though quite elderly is also still alive. Some of the older staff at Silvermans would be able to clue you in more I`m sure about the business and possibly something about Precista as well. The Precista '93 thus far has no known civilian equivalent and what you know is all there is as far as MOD contract watches go..