This is a Waltham RN Nuclear Submarine Pocket Watch, black dial with a non-luminous markers and hands.
The rear case is marked as follows:-
The watch is in excellent overall condition and running well, it has a chrome plated steel case with bevelled edges to front bezel and rear cover. The watch measures 51mm diameter, 69mm to the top of the bow and is 15mm thick. The dial and hands are in mint condition. the case is in excellent condition with some very minor surface abrasion marks to the rear case through usage in service. Waltham 16s nine jewels movement number 31646654, adjusted for temperature and in three positions.
This is the actual watch which appears at the top of page 647 in Konrad Knirm's excellent book on British Military Timepieces