In 1970, the Defence Standard specifying chronographs changed to allow the use of mass produced, two button movements – and over the next 12 years four firms produced chronographs for the British military using the Valjoux 7733, allowing collectors to now call them the “Fab Four”.
Hamilton was the first to begin supplying them in 1970 through to 1972, followed by CWC from 1973 to 1982, with additional batches from Hamilton in 1974, Newmark in 1980 and Precista in 1981. Worn & Wound has a brief account of these watches here.
Most of the watches supplied had luminous dials with the NSN ending 9243306. However, CWC supplied at least two batches of non-luminous watches for use on nuclear submarines, with the NSN ending 9243312, in 1974 and 1975 (and possibly another in 1976 although only one watch has been seen from 1976 to date).
As the cases, dials and movements were all interchangeable, many of them became swapped around during MoD servicing, so it is not uncommon to find mismatched watches. In addition, serial numbers ran consecutively between brands, which makes tracing batches, serials numbers and dial types a somewhat inexact science! Everything below is my current best estimate, but always happy to hear alternative views.
CWC produced over 3,700 of these watches in batches as listed below (I have written the NSNs as they are stamped on the case back).
1973: 0552/924-3306 in the 28xx to 36xx serial number range
1974: 0552/924-3306 in the 38xx to 40xx serial number range
1974: 6BB/9243306 in the 40xx to 45xx serial number range
1974: 0552/924-3312 around the 4050 serial numbers
1975: 0552/924-3306 in the 46xx to 51xx serial number range
1975: 0552/924-3312 around the 4710 serial numbers
1975: 6B/551-924-3306 possibly a batch of 100 numbered 001/75 to 100/75
1977: 6B/551-924-3306 probably a batch of 100 numbered 001/77 to 100/77
1978: 6BB/924-3306 in the 1xx to 25x serial number range
1980: 6BB-924-3306 in the 5xx to 7xx serial number range
1980: 0552/924-3306 in the 7xx to 10xx serial number range
1981: 6BB/9243306 which appears to be batch of 100 watches marked Bxxx/81
1982: 0552 924-3306 in the 15xx to 18xx serial number range
The 7733 has a central chronograph seconds, running seconds at 9 o’clock and a 30 minute counter at 3 o’clock. All the CWC dials were very similar, with a luminous 12 and 6, and luminous indexes, but there were six distinct dial types across the nine years of production. A complete and detailed analysis of all six types of watches can be found in this Collector's Guide blog post.
All the early watches were assembled by Breitling (see the blog post 'The "Almost Fab Five"'), but the manufacturer changed in the 1980s, and it is possible that the later 70s watches were assembled by another manufacturer using only Breitling cases . There are therefore a few notable differences between the different batches.
1973 to 1975 ('Type I'): The old logo without the oval; the numerals 2, 4, 8 and 10 are cut off by the subdials; the CWC logo is in line with the 2 and 10 numerals and the circled T is just below the top of the sub dials; the broad arrow is aligned with the bottom of the subdials. The CWC logo is printed in metallic silver, whilst the circled T, broad arrow, the numerals and minute track are the brass of the dial plate showing through the black print (a gilt dial). The non-lume versions in 1974 and 1975, are the same layout, but without the circled T and with no luminous material, of course.
1975 and 1977 "6B/551" batches ('Type II'): Old logo without the oval; the numerals 2, 4, 8 and 10 are just touching the subdials; the CWC logo is slightly above the 2 and 10 numerals and the circled T is close to the logo above the subdials; the broad arrow is larger and just above the 5 and 7. All the printing is in white ink.
1978 ('Type III'): Old logo without the oval; the numerals 2, 4, 8 and 10 are cut off by the subdials; the CWC logo is above the 2 and 10 numerals and the circled T is below the top of the subdials, giving this dial a distinctive gap between the logo and the circled T; the broad arrow is smaller and aligned to the bottom of the subdials. All the printing is in white ink.
1980 ('Type IV'): Old logo without the oval; the layout of the dial is the same as the Type II dial with the numerals 2, 4, 8 and 10 just touching the subdials, the CWC logo slightly above the 2 and 10 numerals, the circled T close to the logo above the subdials, and the broad arrow larger and just above the 5 and 7. The CWC logo, the circled T and the broad arrow are all printed in metallic silver, while the numerals and minute track are gilt, although the dial is noticeably more of a matt brass than the Type I dials.
1981 ('Type V'): Old logo without the oval; the layout of the dial is again the same as the Type II dial with the numerals 2, 4, 8 and 10 just touching the subdials, the CWC logo slightly above the 2 and 10 numerals, the circled T close to the logo above the subdials, and the broad arrow larger and just above the 5 and 7. All the printing is in white ink, but noticeably thicker than the Type II dial printing and slightly raised off the dial.
1982 ('Type VI'): The new logo in the oval is added; the 2, 4, 8 and 10 numerals are now all clear of the subdials; the circled T moves down to just below the top of the sub dials; and the larger Pheon moves up to be in line with the 4 and the 8. All the printing on the dial is in white.
There are two styles of hands - syringe hands and pencil hands. Syringe hands have slightly rounded, tear-drop shaped ends, and a seconds hand with a pointed tip which is straight and squared off at the other end; whilst pencil hands have straight pointed ends and a seconds hand with a flat tip and a flared tail. Syringe hands can be found on Types I and III; all the rest have pencil hands.
Syringe hands, as well as being found on the earliest watches, also appear to have been used as service hands during the 1980s; hence why they can be found on some watches across all the years.
The other notable difference is in the NSN on the case back - the 1970s watches had deep, large stamping, whilst the 1980s watches had smaller, etched NSNs on the case back. The 1982 series has a two line NSN with 0552 on the first line and 924-3306 on the second line.
'Type I' dial on a 1974, Royal Navy-issued watch. Note the numerals cut off by the subdials, which is characteristic of the 1970s dials. The 'syringe' type hands are correct but the running seconds hand at 9 o'clock should be the same as the minute counter hand at 3 o'clock. Incorrect hands are common on these watches, being replaced during services. Photo Credit: Kibble Watches.
Case back for this watch; note the large, deep stamping of the NSN and issue number. Photo Credit: Kibble Watches.
'Type III' dial on the left on a 1978 watch and 'Type I' dial on the right on a 1974 watch. Note the difference in placement of the CWC logo and circled T, and the white print of both on the 'Type III' dial. Also note the slightly different style of syringe hands. Photo Credit: MBRADIO on MWR.
'Type IV' dial on a 1980 Royal Navy watch, with all correct handset; note the CWC and circled T are close together and the broad arrow is lower on the dial than the 1970s watches. Photo Credit: Mr Jones Watches
Royal Navy-issued watch from 1980: with the 'Type IV' dial; silver gilt CWC logo, circled T and broad arrow; and 'pencil' hour and minute hands. However, the seconds hand looks like it has been replaced with an earlier seconds hand during a service. Photo Credit: omega145012 on Instagram.