JLC Mk 11 6b/346

This is a rare and desirable Mark 11 navigator’s wrist watch, made by Jaeger LeCoultre. The original Ministry of Defence specification describes this watch as, “The wrist watch Mk. 11 is a highly accurate time piece suitable for astro-navigation purposes”. This watch was used by the navigator in an RAF plane in conjunction with a bubble-sextant to calculate the exact latitude and longitude of the aircraft. This method was in principal the same as that used by sailors to calculate their position ever since the development of the marine chronometer by John Harrison in the mid eighteenth century.

The Mark 11 is probably the most iconic British Military watch there is, it was produced in relatively small numbers and only ever supplied by two firms: International Watch Company and Jaeger LeCoultre. Of the two Jaeger LeCoultre supplied just 2,900 pieces making this one of the rarest of military watches. What’s more Jaeger LeCoultre created a special movement, the calibre 488 SBR that was reserved exclusively for this model. A later calibre derived from the 488 was used to power the JLC Geophysic, which was the flagship watch for the house in the 1950s.

This was really the pinnacle of manually wound ‘tool’ watches, and is widely regarded as having the highest quality movement ever supplied to the military (look at the picture of the movement - it simply doesn’t get any better than this in my opinion!) If you need any further convincing about the special power this watch holds over so many people then please visit the website dedicated to tracking this model

The Mark 11 was designed to withstand the harsh environment of a military airplane - it was constructed in such a way as to shield the mechanism from the strong magnetic fields which were present: the dial is made of iron and considerably thicker than that found on a regular watch, an iron dust cover wraps around the back of the movement and joins with the dial to completely enclose the movement and so prevent the influence of magnetism on the time keeping.

The Mark 11 watches were considered such valuable military property that the case and dial and even the movement itself was marked with the military pheon. The watches were subject to an exacting maintenance schedule, indeed initially they were returned to the manufacturer annually for service and for testing to to ensure they conformed to the original time keeping specification. No other military watch was ever subjected to such a rigorous testing and maintenance schedule.

There is an excellent article about the Mark 11 watches which gives fascinating context and insight into them here.

The movement has been fully serviced and the timekeeping is excellent, the watch has a hacking function - that is the seconds are stopped while the time is being set, so it can be set to the exact second. The case has been cleaned, but as with all out vintage watches we have left it unpolished, so do be aware that the case bears the usual marks of wear. The crystal has been cleaned and polished.

I've fitted a period correct Bonklip type bracelet to the watch, which is how it was originally issued. I should be happy to include or replce this with a black nato fabric strap if the buyer prefers. The watch comes with our standard 12 month guarantee.

One of the things that makes the Mk 11 so special is the combination of exacting, chronometer-grade performance and a pure, minimal design. To my mind they are the very essence of horological understatement and quality. Produced in tiny numbers and with a rabid following they represent an excellent investment.  


Case diameter: 35mm
Case material: stainless steel
Strap width: 17.5mm
time keeping: grade A+