The Making of an Instant Icon: Patek Philippe Reference 5236P In-Line Perpetual Calendar

The Making of an Instant Icon: Patek Philippe Reference 5236P In-Line Perpetual Calendar

What is interesting about the title prima ballerina assoluta or, in English, “absolute first ballerina”, is that there is no specific pathway to this greatest of honour. A ballet company can decree it; public opinion and consensus can formalise it. It can even be conferred by one legendary dancer on another, as was the case when Rudolf Nureyev referred to American dancer Cynthia Gregory as “America’s prima ballerina assoluta”. In the case of Phyllis Spira, she was given the title by the president of South Africa in 1984. Perhaps it is this nebulousness that makes this honour so rare. In the history of ballet, there have only been a total of 13 prima ballerina assolutas. But when it comes to the creation of complicated watches — and, in particular, the perpetual calendar — it is for good reason that Patek Philippe is the unrivalled prima assoluta of the watch world.

Among the many significant horological milestones throughout the Genevan watchmaker’s history, Patek Philippe was the very first in the world to create a perpetual calendar wristwatch in 1925. Other industry firsts for Patek include: a retrograde perpetual calendar wristwatch in 1937; a perpetual calendar wristwatch in series in 1941, with the legendary reference 1526; a centre sweep-seconds waterproof perpetual calendar wristwatch in 1944 with the reference 1591; a self-winding perpetual calendar in 1962 with the iconic reference 3448; a perpetual calendar chronograph in 1941 with the legendary reference 1518. Today, Patek Philippe still offers the widest and richest array of perpetual calendars in all of Swiss watchmaking.

Patek Philippe 97975: The first wristwatch with perpetual calendar (©Revolution)
Patek Philippe 97975: The first wristwatch with perpetual calendar (©Revolution)
An illustration of the movement inside Patek Philippe 97975 (Image: Patek Philippe)
An illustration of the movement inside Patek Philippe 97975 (Image: Patek Philippe)
Patek Philippe created another first with the ref. 96 by fitting a retrograde perpetual calendar within a wristwatch in 1937
Patek Philippe created another first with the ref. 96 by fitting a retrograde perpetual calendar within a wristwatch in 1937
The first serially produced perpetual calendar. Launched in 1941 and made in 210 examples over 12 years
The first serially produced perpetual calendar. Launched in 1941 and made in 210 examples over 12 years
Reference 1591: A centre sweep-seconds waterproof perpetual calendar wristwatch made in 1944
Reference 1591: A centre sweep-seconds waterproof perpetual calendar wristwatch made in 1944

An Instant Icon

As if to remind us all of its incredible unassailable history with the perpetual calendar, on 12 April 2021, Patek Philippe unveiled the new reference 5236, one of the most innovative, desirable and, I dare say, instantly iconic perpetual calendars. It is the world’s first perpetual calendar wristwatch to show day, date and month with an in-line display, within a single aperture. One of the reasons that motivated its creation relates to perfecting visibility and legibility for this kind of watch. Patek Philippe’s President, Thierry Stern, says, “As far back as the reference 5970 [perpetual calendar chronograph], my first creation project at Patek Philippe, I was thinking about how to best maximise visibility for the calendar display in a perpetual calendar. I even experimented with a loupe system over the apertures, but eventually rejected the idea. But when we designed the reference 5270, we placed the chronograph subsidiary dials slightly lower, so we could enlarge the apertures for the day and month.”

Patek Philippe Reference 5236P
Patek Philippe Reference 5236P
The N° P-1450 (1972) pocket watch that served as the prime inspiration for the Ref. 5236P In-Line Perpetual Calendar
The N° P-1450 (1972) pocket watch that served as the prime inspiration for the Ref. 5236P In-Line Perpetual Calendar

But there was one watch in the Patek Philippe Museum that consistently intrigued Thierry Stern with its display of calendar information: a pocket watch that dated back to 1972. The owner was clearly a connoisseur, as he had ordered a perpetual calendar pocket watch right at the time when quartz technology was running rampant. He was also clearly an American, as reference 725/4 not only displayed its calendar information in the “American Style”, meaning in the month-date-day sequence, but also in a single straight-line aperture. “I found this display to be very pleasing from an aesthetic perspective,” says Stern. “But then I also liked how intuitive it was to read. On some watches, you have to seek out the information on the dial; here, it was all in one simple line, which could not be easier to read. I explained to my team that I knew that there was a demand for this type of perpetual calendar, and that they should try to create a wristwatch version of this.”

Patek Philippe’s head of watch development Philip Barat (a.k.a. Mr. Plexi for his fondness for plexiglass movement mockups) says, “We loved the idea, of course, but it was not so simple [to implement]. The reference 725/4 is 46mm in diameter, which is normal for a pocket watch. This allows the watch to use a single disc to display the date. But when we worked on designs for a single-aperture, in-line-display perpetual calendar, it became immediately apparent that this one-disc setup would make the date far too small on a wristwatch that measured 41.3mm. Searching for solutions, we arrived at the idea of a date using two discs. One disc for the units of the date and one disc for the tens of the date. They would meet together and form a two-digit date of the perfect size.”

The caliber 31-260 PS QL's in-line display system relies on four disks (of which two are for the date) that are arranged on one level
The caliber 31-260 PS QL's in-line display system relies on four disks (of which two are for the date) that are arranged on one level
The caliber 31-260 PS QL's in-line display system relies on four disks (of which two are for the date) that are arranged on one level

Once the idea was approved, Patek Philippe set about accomplishing it with its typical slavish devotion to perfecting function. The information you see in the single aperture of the reference 5236 is actually comprised of four discs. The disc for the day sits inside the disc for the tens of the date; the disc for months sits inside the one for the units of the date, but when they are underneath the dial and seen through the single aperture, the effect is that of a perfectly linear display. If you look closely, you will see that the tens and the units of the discs are curved in different directions, which gives a small hint to the complexity of the underlying mechanism.

“In order to ensure that the discs turned smoothly and never touched each other, we mounted them on a system of double ball bearings,” explains Philip Barat. “These discs are co-planer, meaning that they all exist on the same plane. There are also mechanisms to ensure the discs never move accidentally. We filed three patents for this customised module.”

The 5236 is from a technical perspective a very different animal in that it contains the first every single aperture housing three displays: day, date and month
The 5236 is from a technical perspective a very different animal in that it contains the first every single aperture housing three displays: day, date and month
The 5236 is from a technical perspective a very different animal in that it contains the first every single aperture housing three displays: day, date and month
A small round aperture on the left of the moonphase acts as a day/night indicator, while a second one on the right displays the leap-year cycle.
A small round aperture on the left of the moonphase acts as a day/night indicator, while a second one on the right displays the leap-year cycle.
The tens and the units of the discs are curved in different directions, which gives a small hint to the complexity of the underlying mechanism.
The tens and the units of the discs are curved in different directions, which gives a small hint to the complexity of the underlying mechanism.

Patek’s communication director Jasmina Steele says, “For Patek, what you see on the front of the watch is only part of the story. The movement for that watch must also be an expression of ingenuity and beauty in design. Thierry Stern is highly involved in every stage of the movement development process.”

“Patek movements express our language; they demonstrate who we are,” says Thierry Stern. “This calibre, the 31-260 PS QL, features a recessed micro-rotor for its automatic winding. Its in-line display alone consists of 118 parts. We made every effort to keep the movement as slim and elegant as possible, and the result is a watch that measures 41.3mm in diameter and 11.07mm in height, which I consider to be the perfect size for this type of complication. And, of course, it receives all the finishing that we are known for across all six of its bridges.”

The caliber 31-260 PS QL with a recessed mini rotor and a customized module is a brand new movement for which three patent applications were filed
The caliber 31-260 PS QL with a recessed mini rotor and a customized module is a brand new movement for which three patent applications were filed

Ode to Legends

Based purely on its single-aperture in-line display for day, date and month, the Patek Philippe reference 5236 would already be assured of a place amongst the greatest Patek Philippe perpetual calendars ever created. But it is also a masterpiece of contemporary watch design that is at once vibrantly modern and pays tribute to one of Patek’s greatest watches, the reference 3448, Patek Philippe’s first automatic perpetual calendar, considered the first in watchmaking.

A greatly admired piece from Patek Philippe's lineage of perpetual calendar watches, the ref. 3448 is powered by the maison's first-ever self-winding perpetual calendar movement, caliber 27-460 Q. (Image: The Watch Club)
A greatly admired piece from Patek Philippe's lineage of perpetual calendar watches, the ref. 3448 is powered by the maison's first-ever self-winding perpetual calendar movement, caliber 27-460 Q. (Image: The Watch Club)
The ref. 3448 is known for its large, perfectly round and thin “disco volante” (“flying saucer”) case, characterised by dynamically attenuated lines designed by Geneva-based case-maker Antoine Gerlach(Image: The Watch Club)
The ref. 3448 is known for its large, perfectly round and thin “disco volante” (“flying saucer”) case, characterised by dynamically attenuated lines designed by Geneva-based case-maker Antoine Gerlach (Image: The Watch Club)
The ref. 3448 is known for its large, perfectly round and thin “disco volante” (“flying saucer”) case, characterised by dynamically attenuated lines designed by Geneva-based case-maker Antoine Gerlach(Image: The Watch Club)
According to industry experts, there were approximately 500 examples of the reference 3448 made between 1962 and 1981 — of which about 100 were in white gold, two in rose gold, and the rest in yellow gold. (Image: The Watch Club)
According to industry experts, there were approximately 500 examples of the reference 3448 made between 1962 and 1981 — of which about 100 were in white gold, two in rose gold, and the rest in yellow gold. (Image: The Watch Club)

The reference 3448 is, simply speaking, one of the most iconic wristwatches of all time. It is the world’s very first self-winding perpetual calendar, and with its large, perfectly round and thin “disco volante” (“flying saucer”) case, characterised by dynamically attenuated lines designed by Geneva-based case-maker Antoine Gerlach, it was also a timepiece that captured the design zeitgeist of its era and the wristwatch choice of pop culture icons the likes of Andy Warhol and Ringo Starr. It is somehow amusing to think of these complex Swiss watches being worn on the wrists of these luminaries as they boogied the night away at Studio 54. The case is a wholly modern 37.5mm in diameter, complemented by sharp, angular lugs which served to focus attention on the large, wide dial, and relatively thin, sharply raked bezel and thin case. This motivated the Italians to bestow on it the sobriquet “Padellone” (“Large Frying Pan”).

Industry experts estimated that there were approximately 500 examples of the reference 3448 made between 1962 and 1981 — of which about 100 were in white gold, two in rose gold, and the rest in yellow gold. There were also examples that were originally white gold, but then modified with platinum cases made by Jean-Pierre Hagmann long after the model was discontinued. The story goes that Philippe Stern gave permission for this to be done to fulfil a special order in 1996 from what was clearly an extraordinarily important client. Of these platinum reference 3448s, one is owned today by none other than watch industry legend Jean-Claude Biver.

In 2009, a platinum reference 3448 was sold at Christie’s with a winning bid of CHF783,000. This actually seems like something of a bargain considering that white gold reference 3448 watches in immaculate condition can hammer in the mid-CHF600,000 range.

In 2009, Christie’s sold a platinum reference 3448 for CHF783,000
In 2009, Christie’s sold a platinum reference 3448 for CHF783,000

It is of interest to note that the watch’s flying-saucer case design, which features a partially recessed crown, could have made it quite challenging to manually wind, which would offer an additional explanation as to why the reference 3449 was never put into serial production. In any case, the reference 3448 is the 20th century’s most iconic perpetual calendar.

Close your eyes and imagine a watch with this complication, and the reference 3448 will come to mind immediately — it is Zen reductive cool to the extreme! The markers are thin, elegant baton-shaped units while the minute track is a stunning series of tiny applied dot markers (in the first three series). The hands are clean, bold sword-shaped units. But where did the seconds hand of the watch go? The same seconds hand that somewhat cluttered the subsidiary dial on the reference 1526, and which took imperious centre stage on the reference 2497, has been altogether dispensed with in Patek’s pursuit of the ultimate act of horological minimalism to render the purest expression of the perpetual calendar.

From Past to Future

Looking at the magnificent platinum-cased reference 5236, you can clearly see the design heritage and its link to its predecessor. (Incidentally, considering the story of the two platinum reference 3448s, how cool was this choice of case material?) The shape of the case is round and UFO-like, and it even features the same style of bezel, as well as the unmistakable short angular lugs of the reference 3448.

The shape of the case in reference 5236 is round and UFO-like, and it even features the same style of bezel, as well as the unmistakable short angular lugs of the reference 3448.
The shape of the case in reference 5236 is round and UFO-like, and it even features the same style of bezel, as well as the unmistakable short angular lugs of the reference 3448.
The shape of the case in reference 5236 is round and UFO-like, and it even features the same style of bezel, as well as the unmistakable short angular lugs of the reference 3448.
The shape of the case in reference 5236 is round and UFO-like, and it even features the same style of bezel, as well as the unmistakable short angular lugs of the reference 3448.

On the aesthetic similarities to the iconic 3448, Stern says, “It is not that I start off wanting to make a tribute to any watch in particular. But more that the 5236 is an expression of everything that is Patek Philippe. For my father and me, every watch in Patek’s history is part of our living legacy and is something that, in turn, I am imparting to both of my sons. If the case for example reminds you of the 3448, that is because the 3448 is part of who we are. While I did not consciously set out to reference it, during the design process I am sure I thought of it in the way I think about the entire living history of Patek Philippe. This is the best way to be a bridge to the future — by creating new watches with new technical functions and new designs, but always be connected to Patek, in the same way as my thought process, that of my father and hopefully soon that of my children, is inseparable from Patek’s history.”

One nod to modern practicality is that while the reference 3448 featured a small recessed crown, Patek has selected a larger and more pragmatic non-recessed crown here. Placement of calendar information is also similar in that the reference 5236’s single aperture is — like the reference 3448’s twin apertures — located at 12 o’clock. Both feature a moon-phase display at six o’clock.

The placement of calendar information on ref. 5236 is similar to ref. 3448’s twin apertures — located at 12 o’clock. Both feature a moon-phase display at six o’clock. The ref. 5236 has slimmer baton markers as well as baton hands, instead of the famous sword hands of the reference 3448 (Images: Revolution and Phillips)
The placement of calendar information on ref. 5236 is similar to ref. 3448’s twin apertures — located at 12 o’clock. Both feature a moon-phase display at six o’clock. The ref. 5236 has slimmer baton markers as well as baton hands, instead of the famous sword hands of the reference 3448 (Images: Revolution and Phillips)
The placement of calendar information on ref. 5236 is similar to ref. 3448’s twin apertures — located at 12 o’clock. Both feature a moon-phase display at six o’clock. The ref. 5236 has slimmer baton markers as well as baton hands, instead of the famous sword hands of the reference 3448 (Images: Revolution and Phillips)

As the reference 5236 integrates the date display into its linear display, it is able to include a seconds hand integrated into the moon-phase display. Now, remember this did not exist in the reference 3448, which had no small seconds display, but it actually references the legendary reference 1526, Patek Philippe’s first serially produced perpetual calendar, which also had a small seconds display integrated into its moon-phase/date subsidiary dial.

Reference 1526, Patek Philippe’s first serially produced perpetual calendar (Image: Christie’s)
Reference 1526, Patek Philippe’s first serially produced perpetual calendar (Image: Christie’s)
Just like the ref. 1526, the ref 5236 has its small seconds display integrated into its moon-phase/date subsidiary dial
Just like the ref. 1526, the ref 5236 has its small seconds display integrated into its moon-phase/date subsidiary dial

While giving nods to previous Patek legends, the reference 5236 remains wonderfully modern. At 41.3mm in diameter, its stunning dial is in a very of-the-moment gradated blue, finished with vertical satin brushing, and boasts a bold minute track which did not exist on the reference 3448, and slimmer baton markers as well as baton hands, instead of the famous sword hands of the reference 3448. While I’d initially hoped to see sword hands on this dial, in the end I feel they would have been a touch over-the-top and busy. Also, I feel that Thierry Stern probably wanted the focus to be on the amazing single-aperture display and thus used slim, elegant hands that would rarely impede the view of this marvellous innovation. Bravo!

Around the moon-phase subsidiary dial, we see a second bold chemin-de-fer seconds track. The overall feeling is a watch that is incredibly elegant and yet has a sporty élan. Slightly contrasting blues are used for the minute track and the subsidiary dial at six o’clock, which add to its vibrancy. A small round aperture on the left of the moonphase acts as a day/night indicator, while a second one on the right displays the leap-year cycle.

Master of the Complication

When I discuss any perpetual calendar wristwatches I always like to go back to the roots of the complication. It was Pope Gregory XIII who, in 1582, instituted the Gregorian calendar, which corrected faults in the Julian calendar. The issue essentially was this: the calendar year (where time is divided into 24-hour days, seven days a week, and 30 or 31 days a month with 28 days in February for a total of 365 days) is actually shorter than the solar year, which is the time taken for Earth to complete one revolution around the sun — 365 days, five hours, 49 minutes and 16 seconds, to be precise. To compensate for this, Pope Gregory XIII added a day — 29th February — to the calendar once every four years. However, this in turn creates a slight overage, so that every 100 years, though divisible by four, the leap day is left out; every 400 years, it is put back in.

So creating a perpetual calendar watch that would keep track of the date and day, compensate for the shifting 30/31-day cycle of the months, and know when February has 28 days and when it had 29, would be an act of extreme horological badass-itude, correct? Well, an English watchmaker named Thomas Mudge did just that in 1762. In 2016, Thomas Mudge’s perpetual calendar watch no. 525 came up for auction and was purchased by none other than the most deserving watch brand on the planet, Patek Philippe.

Earliest known perpetual calendar watch, created by Thomas Mudge in 1762 ( Image: Sotheby’s)
Earliest known perpetual calendar watch, created by Thomas Mudge in 1762 ( Image: Sotheby’s)
First page of the papal bill issued by Pope Gregory XIII that decreed the Gregorian calendar into existence
First page of the papal bill issued by Pope Gregory XIII that decreed the Gregorian calendar into existence

Today, Patek Philippe continues to be the unrivalled master of this complication with the reference 5236 adding a fourth system for displaying the calendar information to its incredible repertory: the first is using the classic combination of two in-line apertures for day and date, combined with subsidiary dials for the remaining information; the second is using a full array of subsidiary dials; the third is using a total of three in-line apertures for day, date and month, and featuring an instantaneous changeover of information; and the fourth is, of course, the amazing in-line single aperture displaying day, date and month.

As such, no other Swiss watch manufacturer can claim greater legitimacy in the creation of perpetual calendar wristwatches, nor possess a more beautiful history with this extraordinary complication. The point is, when it comes to perpetual calendars, Patek Philippe was already perched at the top of the pyramid. With the reference 5236, you could make the argument that they’ve left the pyramid altogether and ascended to the realm of the horological deities where they deservedly belong, with their status as the prima absoluta in Swiss high watchmaking.

Tech Specs

Movement: Self-winding calibre 31-260 PS QL; minimum 38-hour to maximum 48-hour power reserve
Functions: Hours, minutes, small seconds; in-line perpetual calendar; day, date, month, leap year, day/night, moon phases
Case: 41.3mm; 950 platinum; water resistant to 30m
Strap: Navy-blue handstitched alligator leather with 950 platinum fold-over clasp
Price: CHF 110, 000

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