Stunning example!! Great to see another one. I believe that the production period for the entire Royal Navy submarine monopusher series (including the no-lume variants) falls within a broad timeframe of 1945-1976 but I am sure that the no-lume design was only used for the Nuclear Subs in the early 1960s. I have read, but no hard evidence, that only a few hundred Lemania Series III No-Lume Chronographs were ever issued - perhaps 200. Sound about right to you, Amanico?