Unique A6538 UK Military Big Crown Submariner

The Mythical Ref. A6538 UK Military Big Crown Submariner

I would like to present to you the only “still all original” Rolex Submariner A/6538 ever discovered so far which is still in exactly the configuration Rolex delivered it to the British MoD, Ministery of Defense! Enjoy this rarity in all it’s glory in my pictures below.

















Here’s a interesting part from an article written by James Dowling:

When the first series of watches were issued to the divers of the Royal Marines’ Special Boat Squadron (later to become the Special Boat Service), they noted one problem with the watch; it was difficult to rotate the bezel when wearing diving gloves. They also wanted the watch to have solid strap bars; so Rolex decided to make a special model just for the SBS, they initially gave it the unique reference 6540. This number would have made sense as the 6541 was the antimagnetic Mk1 Milgauss, the 6542 was the Mk1 GMT- Master and the 6543 was the amagnetic Mk1 Milgauss.

But as the quantity needed was so small, the initial order was for only 21 watches, it was decided to make these watches as a ‘spin-off’ from the 6538 and they were called the A/6538; however this decision came rather late as the case backs had already been made with the original model number stamped inside. So, all the A/6538 watches bear two references, the original 6540 neatly crossed out by three horizontal lines and their new number next to it. Such a small run of watches were obviously all made together, this can be seen as they all bear the manufacturing date of the final quarter of 1957; no closer dating estimate can be made as all the A/6538 watches have one other common feature; in fact, it would be more correct to say that they all LACK a common feature; unlike all other Rolex Oyster watches, the A/6538s are devoid of a serial number.

None were numbered or ever showed signs of ever having a number between their lower lugs. I mentioned above that the SBS wanted a more usable bezel design, the one chosen had much more pronounced ridges and extended beyond the perimeter of the case, two design features that made it easier to grip whilst wearing diving gloves. Unlike the normal 6538 bezels, which were made of a brass/zinc alloy which was then rhodium plated, these new bezels were made of German Silver (an alloy of Nickel, Copper & Zinc) the great advantage of the German Silver over the previous alloy was that when struck it tended to dent rather than break. This style of bezel proved to be such a success that it became the prototype for the bezels used on the 5512/3 models which followed soon after the A/6538s and has been used on all subsequent Submariners.

The dials of the A/6538 followed exactly the first dials from the civil 6538, which is they were of the ‘Explorer’ configuration with large 3/6/9 in radium numerals on a glossy black dial. There was one touch that Rolex added, instead of the usual ‘200m=660ft’ printed in silver on the dial, these watches (and these watches alone) bore the legend ‘200/660’ in red above the name ‘Submariner’ and there were no units printed after each number. This was the first time that Rolex had used red print on the dial of a sports watch. Unfortunately this unique dial did not survive for very long, the problem was that it used radium as the exciter for the luminous material, and radium was a problem; both in nuclear submarines (where the users of these watches could be expected to travel) and as a hazardous substance in its own right.In 1960 the MoD began to withdraw all watches with radium dials; they were sent to a specialist facility where the dial face with its radium contaminated paint was brushed off under running water. The dials were then polished and reprinted by MoD contractors who produced a reasonable facsimile of the original dials, however, these reprints had none of the delicacy and subtlety of the originals.” Read the whole article over here… 

RPR_50th MSF Diving Team (normally embarked in HMS Diver)

I like to add some notes I got during a recent conversation with Jed McCormack, who also handled the A/6538 and many U.K Military Submariners and has a great interest in MoD watches in general. As there are always different approaches or stories been told, I like to share that information which is important to understand the early U.K. military. When we compare the lowest number and the highest number of the HS-10 CD and 0552/923-7897 we come to the conclusion, if the total numbers where reserved by Rolex for the A/6538 reference , that some 50 examples could have been made. Off these 50 examples some 30 where used for the regular big crown Ref 6538 and the other 20 for the A/6538. Then it is also been said that CD could mean “civilian division”.


The H.S. get in Ref 6150 Explorers in 1953/4 . Next in line is the Ref 6538 in 1956 with red depths and then in 1957 is the improved A/6538 with prototype bezel. For the Ref 6538 they used serial number as stores number. In 1961/’62 we then get the Ref 5512. In 1962/3 all watches are recalled and as in the navy nothing gets thrown away, the Rolex where refreshed. The radium got removed, the dial got reprinted into so called “Burfort” and the dial got luminated with by new standard using tritium instead of radium. If you look closely on those having the military code 0552/923-7897, in most cases you will see the old hs10 engraving underneath! So the navy importantly reissued them to New NATO stores.









Then Rolex also made a Ref 6540 or A/6538 for the UK military of which the most got a new tritium dial reprint. Mike Wood wrote: “As the real danger of radium became apparent, the watches were recalled to the Ministry of Defence in the early 1960’s, where the watchmakers at the observatory at Herstmonceaux Castle in southern England fitted dials with tritium luminous markers, tritium hands, and bezel inserts with tritium markers dots.

The dials were printed for the Ministry of Defence with a very clear and legible 3-6-9 lay-out, with a very tall Rolex coronet, and the T-circle signifying tritium luminous compound. The dials are also referred to as the “Burford dials”. The bezel on the watch is unique to the A/6538, being much deeper than that fitted to the civilian Submariner watch (possibly for better grip when wearing thick diving gloves?), and is made from a metal alloy referred to as German silver. The extra height of the bezel necessitates a “double height” glass retaining ring, but the bezel does not clip very securely and invariably these watches lose their original bezels (replacements are unobtainable)”








The MoD military code 0552/923-7897 with the serial number below… The H.S engraving was before added on this case back.











Check out this little box with Ref 6538 service dials for instance and then you understand why I think we see normal engraved 6538 with these service dials. Question is if the circled T hasn’t been added later to make these dials give more purpose. Only 2-3 of the 55 dials where reprinted “Burford”.













I do hope you enjoyed my write up. If you come across anything that looks like you have seen in this report, feel free to contact me. I think there are still many great vintage Rolex to discover and wonderful stories to be told. It’s my privilege to be able to do this for you. I would like to thank the family for making the deal with me and my lovely wife for the patience she has when i’m hooked on again 😉