I found this movement in with a bunch of english and center seconds chronograph movements. Some of which honestly made me very sad.. Anyway I couldn't find much on Leonard Hall of Louth. One entry in Loome's. All it says is 1901. Although I'm guessing he was one of Hall Bros, Louth, Lincs. Listed in Tony Mercer's Chronometer Makers of the World. 1888-1907. With similar serial numbers. This has/had a center seconds hand but no hack mechanism, it is stem wind/pin and I guess key set with the square below the word "admiralty". So I'm not too sure whether it would be considered a pocket chronometer or deck watch or just a nice free sprung lever watch.