Seiko Chronographs Issued via Ministry of Defence - UK


The Seiko Corporation, through its Seiko UK Ltd. subsidiary, began supplying British Forces with wristwatches in the mid 1980's and continues to do so as of this writing. According to British Military Seiko expert, Ian Fogden, there have been only 3 issued Seiko brand chronographs. Although there is also a rare yellow-dialed "Vulcan" chronograph from Seiko that is reported to have been used by Vulcan bomber crews, these rare watches do not carry issue markings.  According to Seiko UK Ltd. They were most likely a one-off acquisition by "local purchase order" and not Ministry of Defence (MoD) issue watches in the usual sense.

This review focuses on the three Seiko chronographs that are known to have been Ministry of Defence (UK) issue. At the end of this review is an excerpt from an on-line report by Seiko expert Ian "Foggy" Fogden on the mysterious Vulcan Seiko.


Gen. 1 RAF-issued Seiko chronograph

The first RAF-issued Seiko chronograph ( Gen. 1 ) was procured from Seiko UK and issued primarily to Royal Air Force pilots and navigators from October 1984 until November 1990. According to documents I have received from Seiko, 11,307 pieces of this Gen. 1 model were supplied by Seiko to the British Armed Forces.

This Gen. 1 chronograph was contained in a stainless steel case. It carries the highly-regarded, 15-jewel, quartz 7A28 Seiko movement.



As you can see in the above diagram, this Gen. 1 model has three pushers and has all the usual chronograph functions including: split times and 1/10 sec timing, as well as second and minute indicators up to 30 minutes.

A wonderful idiosyncrasy of the Gen 1 chronograph occurs with the register at the 3 o'clock position. This sub-dial measures tenths of a second actively until 10 minutes have passed. At this point the register stops actively measuring time, even though it keeps track within the movement. Once the chronograph is stopped the hand will move to the correct position indicating the tenths of a second that have elapsed. I suppose this was a power saving feature, but it is puzzling until you learn what is going on.

The dial has luminous markers as a result of the application of Promethium 147, a mildly radioactive emitter. The case measures 37mm across, excluding the crown and pushers, and has an inter-lug width of 20mm. Fixed strap bars are used as required by the MoD standard. The crystal is mineral glass and although Seiko no longer carries the original crystal (p/n 300WF0GN00) they have cited reference p/n  300P04HN03 as a replacement.

The NSN for this watch is 6645-99-768-3056. NSN refers to NATO Stock Number which is the equivalent of a Stock Keeping Unit (SKU) or style number in the civilian world. It identifies a particular type of watch that meets a narrow range of specifications and requirements. Required issue markings on the case back also include a four digit serial number followed by a slash and a two digit number indicating the last two digits of the year of issue. (e.g., 1007/84)

The Seiko reference number for this model is: Seiko ref # SPR047

The MoD standard used was for this contract with Seiko was Def Stan 66-4(part4)/Issue 4. The official repair spec was DGSW(N)102. These Gen. 1 watches, however, are no longer maintained by Seiko for the RAF.  Those still in service are being phased out in favor of the newer Gen 2 models.


The Gen 1 Seiko chronograph is one of the most sought after military watches. Because of its relative scarcity, its simple elegance, and its high quality movement, this watch often commands more than US$ 500 from collectors. ItÕs not unusual for a recently serviced example in excellent condition to sell in the US$ 600 range.


Setting instructions for the Seiko RAF Gen 1 Chrono (7A28) can be downloaded by clicking here: Seiko 7A28 Instructions

A Technical Manual with parts lists for the 7A28A, a close cousin of the 7A28, can be found here: Seiko 7A28A Tech Manual

Gen 2 RAF- and RN-issued Seiko chronograph


According to Seiko UK Ltd. Records, after a lapse of over two years Seiko again began to supply the MoD with chronographs in January 1993.  The Gen. 2 chronograph was supplied by Seiko UK Ltd.. The case shape and dimensions are flatter and slightly larger in diameter than the first generation watch, and the Gen. 2 watch also functions differently. 

The new movement was the more prosaic and less costly, non-jeweled, 7T27. The Gen. 2 dial has a small oval date window at "4" showing the day of the month. The Gen. 2 has just 2 pushers, due to lack of the 1/10 second counter.



The dial registers record the following information. The register at "12" is the 30 minute counter used when the chrono functions are on. The register at "6" is the continuous seconds which run whether or not the chrono is on.  The register to the left, at "9", indicates the current hour based on 24 hours. This register, unfortunately, can not be set independently for use as a GMT hand.  The luminous markings are Promethium 147, although the example shown above is the non-luminous version. The case measures 37.7 mm across, excluding the crown, and has an inter-lug width of 20mm. Fixed strap bars are incorporated as per the MoD standard.

The NSN for the watch is 6645-99-814-9181. Required issue markings on the case back also include a four digit serial number followed by a slash and a two digit number indicating the last two digits of the year of issue. (e.g., 0121/94).

The model number inscribed on the case is: 7T27-7A20

Because of the less robust movement in the Gen 2 Luminous model, and the relatively greater availability of this model, this version typically sells for from US$ 350 to 400 depending on condition.



Gen 2 RAF-  RN-issued Seiko Chronograph – non-luminous version


There is a second version of the Gen 2 watch with non-luminous dial and hands. This version was purchased for the Royal Navy, and according to Seiko UK Ltd, primarily for crew on HM nuclear submarines. Presumably it could also be used in any environment where luminous material might interfere with sensitive military equipment. Apart from the lack of luminous material, the watch is identical to that described above, except that the NSN in the case back is different. NATO Stock Number (NSN) should be 6645-99-720-8727. This is because of the non-luminous dial and hands.

According to Seiko records they supplied this non-luminous version for Submarine crews from 1993 to 2000. So watches still in service and those that have made their way to collectors are the only examples of this watch available. One collector has estimated that fewer than 2400 were ordered. This makes it relatively scarce compared with the other Seiko chronos.

Model number on the case is: 7T27 7A20. Required issue markings on the case back also include a four digit serial number followed by a slash and a two digit number indicating the last two digits of the year of issue. (e.g., 0204/93).

         Because of the relative scarcity of the Gen 2 non-luminous model this version typically sells for a slight premium over its luminous twin. Prices start at US$ 450 and can go over $500 depending on condition and provenance.

Setting instructions for the Gen 2 Seiko chronographs can be found here:
Setting Instructions for 7T27 7A20


A WORD or TWO About Straps

NSN 6645-99-527-7059 (Nylon/Leather DEF STAN 66-15 (PART 2)

RAF color Brown. These brown combination leather straps were the standard RAF strap from the early 1970's until the 1992.  Therefore, a properly dressed Gen 1. RAF Seiko Chrono should sport one of these rare combo straps

NSN 6645-99-527-7059 (Nylon DEF STAN 66-47 (ISSUE 2) "NATO strap"

These straps, the well-known NATO strap, have been issue for the RAF since 1992 under NSN 6645-99-527-7059. The correct color should be Grey. These would be the official issue straps for the Gen 2 RAF Seikos.

Earlier, there was a nearly identical NATO style strap made in accordance with DEF STAN 66-15 (PART 1). It was specified in Grey as well, and it was used (under NSN 6645-99-124-2986) by the Royal Navy and British Army (but not RAF) from 1973 until 1992 when the newer NATO standard DEF STAN 66-47 (ISSUE 1) superceded it. Since then the RN and British Army have continued to use the grey NATO strap (NSN 6645-99-124-2986), but under the newer DEF STAN 66-47 (ISSUE 1 and then 2).

The bottom line is that the correct strap for the Gen 1 Seiko should be the brown combo strap shown with the watch below. The correct issue strap for either the RAF or RN Gen 2 Seiko chronos should be a grey NATO strap.

The fabled yellow dial Vulcan bomber crew Seiko chronograph
Excerpted w/ permission from Ian Fogden's website on the Seikos Issued to UK Forces.


A yellow-dialed Seiko chronograph is said to have been supplied to Vulcan bomber crews from 1983. The movement is a 7A38, which is the same as the 7A28 but with the addition of a day date window. All examples that I have seen of this watch have been dated from October 1983. There are no military markings on the watch itself, but it does seem likely that this watch was specially put together for the MOD. Numbers are scarce indeed. One source suggests only 700 were produced – and one would assume that if this had been a commercially available model, then more would be seen.

The reasoning behind a yellow dial was that this was particularly visible in the dimly lit inside of a Vulcan bomber.

Whilst not military marked on the watch itself, I have been told (thanks, Eddie) that the watch was certainly packaged in a typically military style cardboard box, wrapped inside in wax paper, and with the inclusion of NSNÕs on the outside of the box.

Other than the above, little more is known about the yellow dialed Vulcan issue chronograph. My particular example came with a batch of issued 7A28 chronographs, so I have no doubts that this is a genuine military piece. When they rarely come up for sale, prices are high – the last one that I saw, correctly described on eBay, made in the region of £1000.


photo of the "Vulcan" Seiko  courtesy of MWR's "Martin"
ACKNOWLEDGEMENTS: Thanks especially to Foggy for his many informative posts on this subject and to the good folks at Seiko UK Ltd. for the time they took to provide me with important information. Also a special thanks to Alessandro Bon for his diligence in uncovering key MoD standards.

- Ned Frederick, updated 12 April 2006

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