Debuted in 1972, the Royal Oak sized at 39mm was considered at the time to be rather large in size, now recognized by its moniker “Jumbo” by collectors, its nickname traces back to 1973 first by a distributor. A whopping 25cm wrist circumference can certainly earn the title of “Jumbo”. Promoted by Japanese importer Desco in a printed advertisement, the Royal Oak was destined to be worn on the wrist of a famous Sumo wrestler, interestingly the caption also mentioned a normal bracelet size of the watch would be 18cm. A total of 10 links were needed in order to fit his wrist, making it the “JUMBO SIZE” Royal Oak.

It was commonly believed that all cases of reference 5402 bore a serial number found on the caseback (the famous A, B, C and D series). Examples without serial number were known but not accepted by the market which deemed such cases possibly as service replacements.

It is only until recently that in depth research - backed by the robust Audemars Piguet archive - has subverted such belief and in fact demonstrated that “no number” cases are fully legitimate and part of the original production of reference 5402, and - as expected - extremely rare.

According to the archives, such watches were mostly produced in 1975, for a total of 129 pieces. This was a transitional series of watches made after the end of the A series: the original decision was to stop using lettered case numbers, but eventually the company rescinded this choice and went on to the B series.

The present example is preserved beautifully with signs of tropicalization on its dial. The luminous material has also aged uniformly adding collectability to this rare series.