The Longines COSD is one of the rarest and most mysterious of all the British Military watches from WW2. There is a fair degrees of speculation about their original use but I think it’s generally accepted that they were designed for amphibious troops - frogmen and the like. They were supplied during the second world war, but relatively few were issued, perhaps around 200 pieces.

What is known for sure is that the movements, along with dials and handsets were supplied by Longines of Switzerland. There were delivered to the UK without cases, and were cased up in the UK, using domestically produced cases. It’s assumed that the cases were made by Dennison, who were one of the few (perhaps the only?) large scale watch case manufacturer in the UK. Counting against this theory is how relatively crudely the cases are made and finished - they don’t really look like commercially produced items, which is reflected in their “Tuna Can” nickname.

What’s clear is that the watch was designed to be be legible, sturdy, and dependable in the field. The dial features bold Arabic numerals and a crisp railroad minute track, offering the quick, intuitive legibility demanded by service use. The syringe-style hands are luminised and the watch is powered by a very well made and accurate Longines 12.68N manually-wound movement (the movement has the breguet overcool hairspring, something that was designed to ensure good time keeping in all different positions).

This particular watch was owned and worn by Captain N H Harris MBE MN, who is pictured with the watch. Captain Harris was the Second Officer of the SS Fort Stikine, an armed merchant Liberty Ship. On 14 April 1944, the ship, carrying a mixed cargo of cotton bales, timber, oil, gold, and ammunition including around 1,400 tons of explosives with an additional 240 tons of torpedoes and weapons as well as two Spitfires, caught fire in Bombay harbour and was destroyed in two massive explosions. This resulted in the sinking of a further 11 ships in the vicinity and vast devastation in the city surrounding the port area. Some 800-1300 people were killed and 80,000 made homeless in consequence. For his actions in trying to control the fire and subsequently to minimise the impact of the coming explosion, Mr Harris was awarded the Lloyds of London Silver Medal for Meritorious Service. Find out more about it here.