JLC Mark XI
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JLC Mark XI

Through much of World War II, allied aviators were donning the American-made A-11 service watch. While this tough-as-nails timekeeper performed meritoriously for soldiers and airmen alike, Britain's Ministry of Defense found that the production specifications of the A-11 were too broad and resulted in timepieces too imprecise for effective navigation.

As an answer to the A-11, the MoD issued new standards for the watches going to its RAF pilots. The new standard, coded 6B/346, required chronometer-grade performance and anti-magnetic properties. As the MoD did for all watch procurements, they turned to Goldsmiths & Silversmiths Co., Ltd., a High Street jeweler with Royal Appointments who worked with the general public, as well as royalty and government ministries. Goldsmiths & Silversmiths likely approached all of the major European manufactures, eventually giving contracts to two: Jaeger-LeCoultre and International Watch Company.

The resulting timepiece was the Mark XI Pilot's watch.

In addition to the relatively standard features present on the A-11 (center seconds, hacking and a stainless steel case) the Mark XI featured a soft iron dial and dust cover, surrounding the movement with iron on all sides (known as a Faraday cage) and shielding it from magnetic fields that can throw off timekeeping accuracy. It’s worth noting that the Mark XI was likely the first watch designed from the start to be anti-magnetic, a feature that would later become prevalent in military and professional timepieces. 

As cool as the engraved case back and Faraday cage are, it’s a shame that the JLC Caliber 488 can’t be seen, since it’s one of the most beautiful movement of the era, not to mention built to an extremely high standard. The Cal. 488 is one of only a handful of chronometer grade movements from the 40’s and 50’s, designed to be accurate within just 4 seconds per day. While many assume that a military watch such as this would be the epitome of function over form, the gorgeous hand-finished Geneva stripes on the movement are squarely in the realm of haute horology. Putting the military heritage aside, the JLC Mark XI is simply one of the finest watches of its day.

This particular example is one of the cleanest and most lovely examples we've ever come across. With a crisp dial free of blemishes, sharp printing, and even its original "Cathedral" style hands (commonly replaced during contract servicing), this is a Mark XI you won't want to miss!

Details

Stainless Steel case is approximately 35mm (excluding crown). Reference E.161 6B/346 For the RAF. Circa 1949.

Overall condition: The watch is excellent condition over all, with only light signs of wear consistent with age and military use.  Original Jaeger-LeCoultre iron dial is in excellent condition with a lovely even patina throughout. Genuine "Cathedral Hands" are in excellent patinated condition. Original unsigned crown.  Screw-down caseback reads: 6B/346, 3539/48.

Includes two 18mm nylon straps by Crown & Buckle.

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