I was a little sceptical about this but the story checks out. The watch is a standard size 16 Waltham 1908-1609 with 9 jewels, a Swiss lever escapement and a Breguet sprung cut compensated balance with double roller. It is adjusted for temperature and in three positions. The serial number dates
it to 1942.
As confirmed by the catalogue number it was originally
supplied to the Royal Navy during WWII with luminous hands and face, it was retained at
the end of the war, unlike around two million pounds worth of surplus watches
and clocks that were sold off.
Later, following the introduction of Nuclear
submarines in 1960, it was given non-luminous hands and dial so that the relatively
high radiation levels (by todays standards) would not confuse on-board radiation
detection equipment. The case was then stamped "Non-Lum".
The American screw backed case is in base metal case and was made by the Star
Watch Case Company, it is stamped with the military catalogue number, the
Military property mark, the service allocated serial number and "Non-Lum" as
described above.
