At first glance, the present watch appears to be a well-preserved Cosmograph Daytona. The Mk 1 steel bezel, long and thin minutes hand and "Daytona" signature at 6 o'clock are all correct attributes of the beloved reference 6239.

Yet, a small detail on the inside caseback, which may not be obvious to the casual observer, sets this watch apart from its peers. One would usually expect to find "6239" or even possibly "6238" punched on the inside case back of this watch. Yet, this one bears the reference 6242.

A cursory search of this reference number hardly yields results. Yet, investigative research shows that these four digits are stamped on the inside case back of the one and only, reference 6262 Yacht-Master prototype.

One can thus conclude, that Rolex had originally intended to introduce reference 6242 in their line of production, only to scrap the project later. It is even possible that the reference was intended to be made for the mythical Yacht-Master line. Today, only a handful of these "prototype" watches are known on the market, one having resided in the collection of Eric Clapton.

Having already produced the case backs, Rolex decided to use the existing ones in their regular line of production. The present watch was thus fortuitously fitted with a 6242 case back.

It is important to note that the present watch is consigned by its original owner. As such, this example is not just a well preserved wristwatch. It provides a legitimate window into the legend of Rolex, enabling collectors to first, imagine what could be, and second, peek into the firm's history to understand of the inner workings of the mythical Rolex factory.