Probably the only military watch to have seen service all the way from WWII right up to the Falklands; the IWC Mark X is among the most venerable of all vintage wristwatches.

The watch (from circa 1943) was originally designated "Watch, Wrist, Waterproof" or simply W.W.W.; IWC was among a group of 12 suppliers that made these watches to the British Army's  design, giving it the cheeky nickname "Dirty Dozen". The later Royal Air Force Mark 11 draws strongly on the design of the Mark X.

The manual-wind calibre 83 movement is correctly serial-numbered, as are both the inside and outside of the case-back, also bearing the British military Broad Arrow. The outside has a 'civilian' serial number and also a military number. Here's a secret not many people know: if you subtract the military number from the civilian one, the difference will ALWAYS be 1,118,980. This code applies to every correctly-numbered IWC Mark X. 

The condition strongly implies service by the manufacturers; the stainless steel case with fixed strap bars is in exceptionally solid, well-defined condition, whilst the tritium hands and dial markings still exhibit a residual glow.

There are few other watches still available now that are at once good looking whilst carrying the huge cachet of 20th century history.