There's only one undisputed master of perpetual calendars and that's Patek Philippe. The history of Patek Philippe is an interesting story, as the brand was founded in Geneva by two Polish immigrants, Antoni Patek and Franciszek Czapek, in May 1839, Patek Philippe originally produced 200 exclusive watches each year.
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When the co-founders' business partnership dissolved in 1845, as Czapek decided to go solo, Patek was joined by French horologist Adrien Philippe, who became the brand's creative force at the forefront of innovation. Complex mechanisms were Philippe's speciality. He had already invented a mechanism to wind and set watches using a crown, rather than a key. 
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His skills saw increasingly complex mechanisms becoming a key feature of Patek Philippe watches. The company patented its legendary perpetual calendar wristwatch in 1889, which was a major historical moment in the fashion industry that left its mark.

Always striving for perfection and refinement, in 1898, the brand scaled the movement down further to power a ladies’ pendant watch. This was quite a remarkable innovation since the market for women's watches at the time was relatively small and didn't have a reputation for cutting edge precision.
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In 1925, the movement was re-cased in a relatively small 34.4 mm yellow gold case. The perpetual calendar is so challenging to create because each of its individual calculations requires its own set of mechanisms. These include the hours, minutes, seconds, month, date, day of the week and the moon phase.
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Some of the prototype watches designed by Patek Philippe were so complicated that their development took up to 30 years before they were ready for production. The beauty of the Patek Philippe Perpetual Calendar range was the creator's ability to cram all of the complex mechanisms into a watch that wasn't much larger than its simpler counterparts.

The innovations of Patek Philippe Perpetual Calendars just kept on coming. In particular, in 1941, the legendary Patek Philippe reference 1526 was the world's first perpetual calendar watch for the general public. In those days, complications were a rarity, even in the world of luxury watches.
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While today, they can be found in almost every respectable watchmaker’s collection, during the war, they were reserved for private commissions. The reference 1526 had introduced a perpetual calendar into the brand's range of watches for general consumers, rather than for Patek Philippe's wealthier followers.

Collectors can choose from a wide range of models today, all made with equally precise craftsmanship, such as the Patek Philippe reference 5159G white gold Perpetual Calendar wristwatch, with a price tag of around £30,000. The Patek Philippe reference 5050, a yellow gold Perpetual Calendar wristwatch, with 24 hours, moon phases and a leap year indication, sells for up to £50,000. 
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Celebrity wearers of Patek Philippe Perpetual Calendar watches include global singing superstar Ed Sheeran, who has been photographed wearing a reference 1518 on stage. He reportedly has two different models and has been seen wearing both of them on the same night, one on the red carpet and the other when performing on stage later!