5513 RN MilSub, I.72 caseback, issued ca. 1976--posted by Haywood Milton

Note: "This biggest batch [of Rolex Subs for the Royal Navy] (but not all batches) has 1.72 case-backs, though issue itself from same did not seem to occur before 1975. Of course, there were earlier mil subs, but I am referring to this batch by manufacturing case number specifically." - HM