The case has a history through 1936 and the movement through 1921. The details are in a Word document I uploaded up thread.
The H.S. designations were applied to the cases sometime after 1939--probably after 1942. The movement number has been scratched into the inside case cover. The box style is consistant with Hydrogrpahphic Service boxes. The blank label is post WWII. Movements, cases and boxes routinely got interchanged during depot maintenance. See some of the deck watch descriptions in the Greenwich catalog:
http://www.nmm.ac.uk/collectio...bject.cfm?ID=ZBA0080Craig, in his reply on the H.S. thread thinks the order for the H.S. designations dates to 1942.
It is logical that the marriage would have occurred early in WWII because that is when the need for large numbers of navigational timepieces occurred. The scratched movement number on the case implies a need to keep the two together from some point on. This would occur to a depot technician but probably not to a later (post HS) restorer. I don't think the box is original to the watch but it would be a convenient way for the Hydrographic Service to store and then surplus the watch after the war.
I would like to find out the WWII history of the watch but I don't know yet whether those records were kept.
The best news is that I now own the watch. I was researching it for a friend. He said. "you seem to like this watch, make me an offer." I did, he accepted and it now graces my desk alongside two Canadian 3992B's. More on those later.
Paul
Paul Middents