UK military codes from WW II to early 80s .

Jan 18, 2020,12:26 PM

here is the english translation/upgrade of a work about UK military codes I have written some years ago for the italian magazine  " Orologi & Market " :
< this subject would deserve a medium size book, however I thinks that is interesting to share some basics informations particularly referring to military watches delivered to UK Forces from the 50s on.
In the short space of a single work it's impossible to describe all possible situations and every peculiar chances .. so all owners of eventual " exceptions " are kindly requested to share them.
                                                                          WW II and earlier engravings
During the WW II and sometimes up to the 2nd half of the 50s the most common assignations were the followings :
1) British Army ( that after Cromwell is not anymore " Royal ", a term granted only to single units distinguished by bravery or loyalty ) :
--WWW (=Waterproof Wrist Watch ) followed by a capital letter identifing the manufacturer ( for ex. K for Timor , Y for Omega and F for Longines ) ; sometimes also the manufacturer name was engraved on the back ;
-- the broad arrow ( a stylized arrow pin that identifies the item as Crown property ) ;
-- one or two series of digits that show the progressive delivery number and sometimes also the watch case number. 
so for ex. a Timor watch could have this engraving :
broad arrow
8211 ( delivery number )
36791 ( case number ).

2) Royal Air Force :
-- broad arrow
-- abbreviation 6B ( sometimes 6BB or 6A or 6E ) followed by a number ( usually 3 digits ) identifying that particular model and his type  ;
-- year of delivery and progressive assignement number ;
-- sometimes in watches delivered during the WW II there was also the abbreviation " AM " (=Air Ministry ) ;
so for ex. a Longines could have these engravings :
broad arrow ( often not present if there is " AM " )
About the point of delivery numbers is really important to enphasize that every new year the assignement number was not beginning again with " 1 " ( or " 01 " or " 001 " or .... ) but with the very first free number ... so for ex. if in 1945 the last number assigned had been " 6431 ", in 1946 the first watch would get the number " 6432 " .
This procedure was obviously followed by all UK Forces. 

3) Royal Navy ( that includes also Royal Marines and Fleet Air Army ) :
-- broad arrow ;
-- HS (=that stands for Hydrographic Service ) , used also for other branches belonging to the Navy such as R.Marines,
followed by a number ( from 1 to 11 ) defining type and/or destination ;
for ex. HS 9 defines a wrist-chronograph and HS 10  a divers watch ;
-- progressive assignement number and/or case number .
so for ex. a military Rolex Explorer ref. 6150 could have :
broad arrow
HS 10 CD ( Clearance Diver )

                                                                                    Hybrid engravings

Since the beginning of the 50s we find backs with series of numbers often wrongly related to Nato Stock Number code :
a) " 0552 " that is a UK military code choosen by the Ministry Of Defence ( and not a " NATO prefix for UK Navy watches " ) for watches delivered to the Navy ;
b) " W10 " : that is another MOD code for British Army watches ;
these codes can be defined " hybrids " as they contain either parts of national classification ( such as " W10 " ) and parts of the NATO one.
Some typical example :
I) Omega " fat arrow " , with these back engravings :
-- " 6645 " (=NATO code for a wrist watch , a number we shall also find in the Nato Stock Number ) ;
-- broad arrow ;
-- " 101000 "  : a 6 digit nunber that indentifies the particular model ( later this number will have 7 digits ) ;
-- 6B ( RAF )
-- 542 , a MOD number that shows the type , in this case a pilot wrist watch ;
-- progressive delivery number ;
so the complete code would be :

2) for a RN Hamilton chronograph we should have :
-- broad arrow ;
-- 0552 ( R.Navy watch )
-- 924-3306 ( model + type code )
-- progressive delivery number ;
so that the complete code would be :

3) in the same model described above but delivered to RAF we should have seen :
--6B ( or 6BB )
-- 551 that is the type code used for this model by RAF :
-- progressive delivery number ;
so that the complete code would be :

NOTE : sometimes the 7 digit type code will remain unchanged in the Nato Stock Number ( as for Rolex milsubs ) , sometimes will change as we will see .

                                                                              Nato Stock Number

NSN arrives around the middle of the 60s : it was studied to make a perfect identification within NATO of every kind of supplies ( from bullets to spare parts for laundry machines) , in order to have an easy classification and supply of all items already in use or expected to be used in the military environment.
It consists of 13 digits so defined :
A) the first 4 digits define the SPECIES (=sort ) code ; in other words they define " the family " to which belongs the item , so for ex. 5305=screws , 6645=wrist watches ;

B) digits 5 and 6 are the code of the country who has given this NSN , that can be different from the country who has made the item ; so for ex. a watch produced in France can have the country code of another nation , such as Germany or USA .
Some country codes are :
-- from 00 to 09 : United States
-- 99 : UK
-- 12 : Germany
-- 14 : France
-- 15 : Italy

C) the last 7 digits are the own item code : so all 7 digits codes describe an item ( or a group of items with extremely close features ) within the nation that has requested this particular NSN.
This means :
1) the 7 digits code is defined as " with no inherent significance " , so it doesn't give any evident information about the item
( in other words it's completely at random ) ;
2) it's progressive and depends on the time in which the codification has been requested ; for ex. " 545.7078 " can be a lamp and the following number ( " 545-7079 " ) a ground-air missile.
3) some 7 digits codes have been used by more than a country ( as for watches ) some only by the country who has created that code.

Some UK examples :

*) a British Army Smith watch delivered in 1970 had this NSN : 6645-99-961-4045
and the complete delivery code would be :

** ) Omega SM 300 and Rolex milsubs delivered to the British Army  had the same NSN :
so for ex. the complete code for a Seamaster would be :

*** ) Omega SM 300 and Rolex milsubs delivered to the R.Navy still had an hybrid code and not a NSN number             
so for ex.
--- a Rolex 5513 had this code :
-- an Omega SM 300 the following one :

FOOTNOTE : Up to the present days there is no proof that progressive delivery numbers could start every year from a number lower than the higher one given in the previous year. >

More posts: 55136150ExplorerSeamasterSeamaster 300Submariner

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Comments: view entire thread


Very interesting reading Marcello !

 By: DrStrong : December 20th, 2013-07:02
if I remember well, you have a very nice military Omega Sm300 ;-)

A reference post, Marcello. Very helpful and interesting. To be saved!

 By: amanico : December 20th, 2013-07:21
Huge Thanks, my friend... By the way, Marcello, do you happen to know what " AM " stands for on a Blancpain Fifty Fathoms from 1967 / 1968??? Best, Nicolas

like in this Milspec 1 ???

 By: marcello pisani : December 20th, 2013-07:42
not certainly " Air Ministry " as this < AM > is an engraving made at the Blancpain factory . this abbreviation appears only on some Milspec1 and not on other FF ( AFAIK ) and neither on TR 900. the 3 digits figure is in my opinion the case number ....  

:) I know this one very well, as it was mine. :)))

 By: amanico : December 20th, 2013-09:33
Yes, like this one. I tried hard to find something about the true meaning of AM, in vain.... Thanks, Nicolas

well ...

 By: marcello pisani : December 20th, 2013-14:18
I have seen another 2 or 3 with the same abbreviation .. all with very low case numbers ( under 1000 if I remember well ) ... worths study some more ...

The highest I know is this one, the 103.

 By: amanico : December 20th, 2013-14:20
Then, I know the 38, the 57, the 80 and another one, whose SN has been totally scratched.... Very rare version, for sure! Best, Nicolas

Did you call?

 By: Baron - Mr Red : December 22nd, 2013-06:03

Damn sensual!!!

 By: amanico : December 22nd, 2013-06:14


 By: Baron - Mr Red : December 22nd, 2013-06:19 see Marcello's take on the marking. Bottom line, i suspect, is that we will never get too far on it. Air Ministry...i like that best so far!! I don't think it makes sense to stand for Anti-Magnetic as it has that written in full!!!


 By: Baron - Mr Red : December 22nd, 2013-06:29
......its the pleasure of the watch and its mystery!! ...  

same damned AM 103 ?????

 By: marcello pisani : December 22nd, 2013-08:34
if so ... a real small world .. isnt ' it ???? LLLOOLL

Yes! LOL!!!!

 By: amanico : December 22nd, 2013-08:36

a true restless poor baby ......

 By: marcello pisani : December 22nd, 2013-08:41
really mint conditions btw ..... unfortunately Blancpain lost all his old records in a fire during the 80s .. so they can't tell us where this watch ( and others with that misterious abbreviation ) have been sold.

Yes, sadly, but...

 By: amanico : December 22nd, 2013-08:45
It seems that they way they have been found, t least some of them, indicates a military provenance... Best, Nicolas

it IS a small world!

 By: Baron - Mr Red : December 22nd, 2013-09:10
Same 103 But not restless!

so he has found a steady place at last !!

 By: marcello pisani : December 22nd, 2013-09:22
glad .. as this watch ( I had in my hands some years ago ) is in really fine conditions. at that time ( 6-7 years ago ) the average quality of watches was far better than now ...


 By: Baron - Mr Red : December 22nd, 2013-09:31
......took this one this time last year.... Indeed, it is in lovely condition and sits VERY happy in my collection!!!

yes but this wasn't a watch

 By: marcello pisani : December 22nd, 2013-11:26
new to the market : if you have done ( like some of us ) in the last years a record of uncommon and particular watches ( like this one ) arrived " fresh " to the market ... you should have easily noticed that the average quality has dramatically decreased... 

Wow, Great post Marcello!!! Thank you for putting this info together :-))))

 By: Rick-O : December 20th, 2013-19:21
What a great reference! Cheers buddy :)

Superb info....

 By: Baron - Mr Red : December 22nd, 2013-06:30
.....Marcello...again....thanks for sharing this.....paints more colour into so many places.

it's my pleasure !! nt

 By: marcello pisani : December 22nd, 2013-08:35

This is a great post.. Have read and re-read it..So interesting ! :)

 By: hs111 : December 23rd, 2013-19:56
Thank you for this compilation ! Have already bookmarked it .. Happy Festive Season and All the Best, hs