Sterile 6BB–The ‘Lost’ Navigator

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The 1976 MOD issued Sterile 6BB watch is somewhat of a mystery to collectors of modern British military watches. It’s cousins, the Hamilton and CWC tonneau-shaped W10 General Service watches are well-known and easily identified. See here for more information on these models:

The CWC G10 navigator was the logical next model and the quartz version replaced this 6BB version around 1980.


  • Case is W10 tonneau shaped of monobloc construction
  • Movement is only accessible from the front through the crystal
  • The size is similar to Hamilton and CWC W10’s (but not exactly)
  • It was only issued in 1976
  • Approximately 2,000 were issued
  • The dial and case are sterile e.g no manufacturer’s name or logo is applied
  • Dial design is almost identical to DEF STAN 66-4(Part 5) Issue 2, Figure 1, Page 8
  • The inside of the case bears no markings
  • 6BB prefix would indicate it was to be issued to the Royal Air Force


The movement in the sterile 6BB has been identified as being based on the A.Schilds AS 2160 17 jewel manual wind, 28,800 bph, but with a micrometer type of adjuster replacing the normal regulator. The micro adjuster appears to be very similar to that used on the Valjoux 7750 movement.


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