In popular cultural discourse, it’s hard to imagine the Royal Oak as anything but the definitive everyday luxury sports watch. When Audemars Piguet unveiled its inaugural version -- the Ref. 5402ST -- before the industry in 1972, the Royal Oak appeared in the guise of a time-and-date model. None of the uproar centered on its apparent lack of complexity. Rather, its daring 39mm case size, stainless steel construction, and “utterly inconceivable” price-tag (nearly five times more than most steel watches of the era) were the primary objects of conversation. Fortunately, through the dark days of the Quartz Crisis, it became clear to AP that the design’s basic concept -- a ‘sporty chic’ stainless steel construction with an integrated bracelet -- would be pivotal to securing the company’s future.

Almost by necessity, that epiphany entailed an expansion of the Royal Oak collection; and in 1984, collectors were able to acquire the first ever examples of the Royal Oak Perpetual Calendar (‘QP’). Since then, there have been a string of references -- some with mother-of-pearl dials, even a one-off version with a full pavé setting -- though almost all of these exhibit a strong sense of continuity with what came before.To better illustrate this, we’ll begin by examining the Ref. 5554/25554 (a.k.a. the ‘first Royal Oak QP’) and the ultra-thin movement that powered it; before turning our attention to its younger, more prolific cousin -- the Ref. 25820 (which also happens to be listed on our website).

The Calibre 2120/8000 | Audemars Piguet

Royal Oak 5554/25554: Modernising the Perpetual Calendar

AP’s renown in the field of perpetual calendars is a matter of historic record: during the early 20th century, up to a dozen were manufactured per year as pocket watches. By the 1940s, the company had developed sufficient skill to produce them as wristwear. For present purposes, the most important of these was the Ref. 5516: a round-cased watch employing a 4-register layout that remains popular in the field of perpetual calendar design -- even today. Both the 5516’s first and fourth series contributed stylistically to the later Royal Oak QP: with the former exerting a clear influence on the configuration of dials; and the latter serving as inspiration for the leap-year indicator found specifically in the 25820.

Though the first Royal Oak QPs wouldn’t reach clients’ wrists until the mid-1980s, their entire existence was predicated upon a spate of technical breakthroughs having been made in the previous decade. In 1978, AP unveiled the calibre 2120/2800: an ultra-thin, self-winding movement conceived behind closed doors. It was chiefly the work of three men: Michel Rochat, a veteran watchmaker at AP; Jean-Daniel Golay, founder of the Technical Department; and Wilfred Berney, head of After-sales. Consisting of the same self-winding movement found in the original Royal Oak ‘Jumbo’ (augmented with a perpetual calendar module supplied by Dubois Dépraz) the 2120/2800 initially saw service in the Ref. 5548 -- a run of round-cased QPs which, upon release, were recognised as the thinnest perpetual calendars ever made.

Audemars Piguet Royal Oak ref. 5554 | Antiquorum via Revolutionwatch.com

Taking into account the historic conditions under which the 2120/2800 was born (i.e. at a nadir for the Swiss watch industry) it’s difficult not to be impressed by the sheer audaciousness of what AP was attempting. In his book Audemars Piguet, horology writer François Chaille puts it thusly: “The term revolution is not too strong to describe the impact of [AP’s] perpetual calendar. It represented a veritable watershed in the history of horology...this move was typical of the daring traditionally associated [with the brand], which among all the leading makers of mechanical watches has proven to be the most ‘resistant’ to the hegemony of quartz (today, only four percent of its output has quartz movements)”.

Consequently, following a positive reception to the 5548 -- over 2,000 examples would be made during the reference’s 14-year lifespan -- the powers that be embarked upon a mission to modernise the perpetual calendar. At the time, the burgeoning Royal Oak collection was far from the commercial powerhouse it is today, prompting then-CEO Georges Golay to task Jacqueline Dimier with fusing the watch’s sportif, bleeding edge aesthetic to what was, in many ways, a heritage complication. Fortunately, few people were better suited: as AP’s Head of Design, Dimier had already completed the first 29mm Royal Oak, providing her with invaluable firsthand knowledge of the eponymous design’s nuances. The challenge lay in how best to square that against the complicated display and architecture of the perpetual calendar.

Between the ultra-thin calibre 2120/2800 and Dimier’s aesthetic savvy, the 5554 was born. The fact that every Royal Oak QP between 1984-2015 utilised the dimensions of that reference is a testament to its influence: despite the multi-part case construction and perpetual calendar module, the 5554 sported dimensions of 39mm x 9.3mm -- making it as wide (and only negligibly thicker) than the original ‘Jumbo’. A rare reference by any metric -- and particularly for a company as small as AP -- only 279 known examples of the 5554 are in circulation. As was common during the ‘Yuppie Decade’, the vast majority of these were released in yellow gold, alongside a handful of steel models and a singularly rare pièce unique in platinum.
While it’s impossible to deny that the 5554 is responsible for ‘setting the tone’ of Royal Oak QPs over the decades, it also possesses a number of aesthetic peculiarities that help set it apart from later references. Most of these reside on the dial. In their original incarnation, each 5554 was fitted with a ‘Mark 1’ dial: these differ from the ‘Mark 2’ in the uniform size and style of the signature. (In the Mark 2, the “A” and “P” serifs in “Audemars Piguet” are noticeably taller.) Additionally, these authentic Mark 1 dials were all decorated in a smooth “grey opaline” finish -- an internal designation confirmed by Michael Friedman, AP’s Head of Complications. “These early [Royal Oak QPs] had smooth dials without the hobnail decoration you see in later models,” says Friedman. “If you find a 5554 and it has a different dial, it’s likely it was swapped in during a service.”

The Royal Oak ref. 25820

Royal Oak 25820: Serialising the ‘sport chic’ complication

The basic template set down by the 5554 was followed across ten ‘references’: six of which, when taken together, produced a miniscule 11 watches. The shift to a new paradigm came in 1998 with the launch of the 25820. According to Wei Koh, founder of Revolution Magazine, “this is when the 2120/2802 with leap-year indicator first…[entered] regular production”. The movement’s “02” designation identified it as a descendant of the original 2120/2800. Though functionally identical to the latter, the new calibre represented the first ultra-thin perpetual calendar movement to be manufactured serially by AP, which also included a leap-year. This distinction is a minor yet important one; as three years prior, AP had in fact already cased the new calibre up in a rose gold limited edition -- made to celebrate the brand’s 120th birthday. (For added historicity, the leap-year indicator in that release closely followed the layout and typography of that present in the 5516.)

Tangents about limited editions aside, the present 25820 hails from around the end of the reference’s lifespan -- manufactured circa 2012. Again, that date bears certain cultural significance, as it is during this period that AP transitioned the basic time-only Royal Oak to a size of 41mm (a development that, unsurprisingly, would go on to influence the current Royal Oak QP’s design). By now, having made numerous incarnations of the Royal Oak as a perpetual calendar, AP released the 25820 in a plethora of case-and-dial combinations, drawing on its 20+ years of experience with the style. Naturally, these include the rare bi-metal 25820TR in tantalum; the ‘salmon’ 25820PT; and no less than three variations on the colour blue. The example we’ve curated combines a stainless steel construction with white tapisserie dial -- one of the more ‘common’ configurations (albeit only in the very specific context of this reference).

The Royal Oak ref. 25820

As previously alluded to, the movement powering this 25820 is, in myriad ways, identical to the previous calibre 2120/2800. The biggest deviation is of a technical nature, with the leap-year now indicated inside the sub-dial housing the date display. On the caseback, the bridges and regulating mechanism are laid out in a manner visually consistent with the 2120/2800 (note the island-style bridge at 4 o’clock). Similarly, the standard of finishing is pitched at a level that’s as refined as what you’ll find in the original Royal Oak QP movement, with the exception of one element -- the rotor. In the later 2120/2802, the rotor is substantially more elaborate than its predecessor: the winding mass itself is skeletonised (allowing the user to more easily glimpse the bridgework below) with a radius that has been used to illustrate elaborate, baroque-style hand engraving. To bring matters full-circle, it’s impossible to consider the appeal of the Royal Oak QP without recognising the influence of its simpler predecessor. As the classic two-handed archetype of the Royal Oak -- whether it be in the guise of ‘vintage’ or ‘modern’ -- becomes ever more popular (translation: unattainable) collectors are shedding new light on all pages of the style’s back catalogue. As far as variations on a theme go, this 25820 scratches many of the same itches introduced in the ‘Jumbo’: it was among the last handful of Royal Oaks to be made in the 39mm format; utilises a movement that is the by-product of important historical events; and nails the balance between tradition and modernity. Where perpetual calendars are concerned, that’s certainly no small feat.

To bring matters full-circle, it’s impossible to consider the appeal of the Royal Oak QP without recognising the influence of its simpler predecessor. As the classic two-handed archetype of the Royal Oak -- whether it be in the guise of ‘vintage’ or ‘modern’ -- becomes ever more popular (translation: unattainable) collectors are shedding new light on all pages of the style’s back catalogue. As far as variations on a theme go, this 25820 scratches many of the same itches introduced in the ‘Jumbo’: it was among the last handful of Royal Oaks to be made in the 39mm format; utilises a movement that is the by-product of important historical events; and nails the balance between tradition and modernity. Where perpetual calendars are concerned, that’s certainly no small feat.

The Royal Oak ref. 25820

Randy is a Hong Kong-based luxury journalist specialising in watches and the beverage industry. For other articles and regular updates, you can follow him on social media.