According to the Archives of Audemars Piguet, the present watch is part of a series of only three examples of reference 5516, numbered 66'135 to 66'137. The ébauches were made in 1955, finished and encased and sold in 1959. This watch, the last one of the series, was actually the first one to be sold on 25 July 1959. These three watches are most likely the only 3 examples of any of Audemars Piguet's perpetual calendar wristwatches to feature an aperture for the moon phases to 12 o'clock. No other model is known publicly or from literature with the same dial layout but show either the same crescent-shaped aperture or a subsidiary dial for the moon phases positioned to 6 o'clock.
A second series of reference 5516 bearing movement numbers 73'011 to 73'016 was made as of 1957, however all with the aperture positioned to 6 o'clock.
An advertisement from the mid 1950s shows three different references, 5513, 5514 and 5516, the present model. The first two feature a full calendar, only the last was equipped with the perpetual calendar mechanism. It is furthermore the only example with the aperture for the moon phases to 12 o'clock (see Audemars Piguet by Gisbert L. Brunner, Christian Pfeiffer-Belli, Martin K. Wehrli, p. 71). The first example of reference 5516 bearing movement number 66'135 is described and illustrated on p. 234, pl. 315, op. cit., next to the image and description of watch number 73'012 from the second series of this reference.
The watch here offered for auction for the first time ever must be considered one of the most important and appealing Audemars Piguet wristwatches known to exist. The perfect combination of mechanical complexity, attractive design composed of the large yet elegant case and superb two-tone dial and its extreme rarity lift this trophy to the elite of postwar watchmaking.