1980 CWC G10 'Fatboy' - field modified to 'Navigator' spec
Unique field modified watch in lovely condition
£465.00
Out of stock
In 1980 the Ministry of Defence procured its first quartz watches in the form of the CWC 'G10', which during that year replaced its predecessor, the mechanical 'W10' watch. The 1980-82 G10s have become known by their nickname - 'Fatboy' - due to the depth of the case required to accommodate the ESA/ETA 536.121 movement.
The 1980 issue watches had the the old 'no circle' CWC logo on the dial - the same as the mechanical W10s, but also was marked 'Quartz'. Unlike later G10s, the case back does not have any service code to designate whether the supply contract was through the Army, RAF or Royal Navy/Marines.
The ESA 536.121 movement fitted to early G10s had provision for calendar works (day and date), and although most of the relevant components were either removed before they were fitted or during subsequent servicing/repairs, SOME of them still had a functioning date disc, even though it was hidden behind the dial (some collectors have commented on the ‘ghost stop’ when pulling the crown on a Fatboy G10 - the redundant day/date quickset position). A few enterprising quartermasters carried out a field modification by cutting a window in the dial converting the standard G10 into a ‘Navigator’. These modified dials crop up every now and again. This example has been sympathetically restored to full working condition, with the movement serviced, the case parts cleaned, and new parts used where necessary. The original field modification was very neatly done, the rest of the watch is in very clean condition as described in the condition report below.
The watch is supplied on a quality 18mm heat bonded 'James Bond' NATO strap.
The case is in very good condition with general small marks from use/wear. The case back has some marks from use but no significant strap burn. The case back has the correct markings including the NATO stock number, serial number and issue year. The crystal is a replacement with matte tension ring fitted. The dial and hands are in very good condition. The lume, which is a great colour, has been repaired with colour matched 'low glow' luminous compound. Please refer to the images to make your own judgement about the cosmetic condition of the watch. The images form an important part of the description.
The watch was subject to a full stripdown, clean and service in January 2026. The case parts were stripped and ultrasonically cleaned and the ETA 536.121 movement was serviced.
The movement was fully stripped, mechanically and ultrasonically cleaned using waterless solutions and hot air dried. The movement was rebuilt and lubricated using Moebius oils. A new OEM crown and stem were fitted along with a replacement seconds hand. Images of the movement rebuild are included in the listing. All the gaskets were also replaced and greased, including the back gasket, the battery hatch and crown gaskets. The watch hacks and sets from the crown correctly, date quickset works and the date automatically advances at midnight.
The watch was regulated on a quartztester machine and is running on the bench at +/-0.00 seconds per day, which is well within the +/-10 seconds per month specification. Note that accuracy may differ from this when in use.
The watch is absolutely suitable for everyday use, but it is vintage watch so is not recommended for sports or use in extreme conditions. The watch has not been pressure tested so water resistance is not guaranteed. This watch is covered by our waterproof 6 month guarantee.
Issued: Yes
Issue details: UK MoD - field modified
Date of manufacture: 1980
Production numbers: c12700
Movement: ESA/ETA 536.121
Diameter: 36mm
Lug width: 18mm
Hacking: Yes
Case back: Snap
Screwdown crown: No
Bracelet: NATO
UK MoD issue with original field modification to 'Navigator' spec.
The original 'Fatboy' G10 - essential addition to any military watch collection
Original ESA 536.121 quartz movement
Recently serviced with NOS circuit board
Great condition
Supplied on new heat-welded NATO-type strap
6 months non-waterproof guarantee
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