By Stauffer Son & Co. London. This stopwatch has a split-second chronograph action and was used to perform complex performance tests, bombing runs and for navigational use. White metal case approx. 5.5cm diameter. Black dial with subsidiary dial measuring seconds from 1-180 and minutes from 1-3. Arabic numerals. It has a keyless Swiss movement with a centre second hands rated to one revolution per three seconds. It is provided with two control knobs. When the large central knob is pressed and held the movement starts and will stop when released. The side knob resets both the main and subsidiary hands. The case is in good used condition with King's Crown, Air Ministry markings on the back. Both knobs function correctly as long a sufficient pressure to the main knob is made and maintained. The watch bow is original and the dial is also in excellent condition. The back cover is hinged and a hinged dust cover sits beneath. There is some scratching/burring where these have been opened. The movement works correctly although as mentioned above, due to the pressure needed it can take a couple of presses to start. Unusally there is a small compartment within the case containing spare parts. A very high quality timepiece. Stock code C20596.