A Photographic History of Patek Philippe Perpetual Calendar Chronographs

To understand why Patek Philippe is the industry leader requires a separate article which I will write later, but of all the watches that Patek makes, two stand out the most: The perpetual calendar chronograph and the minute repeater. 

Patek made the first perpetual calendar chronograph with ref. 1518 in 1941 and has been making them continuously since. They have all been column wheel chronographs in the most traditional way with the column wheel covered from direct view. Below is a section taken from a Bonham'sauction describing the history of the Patek QP CH (Quantieme Perpetuel, Chronographe)

Ref 1518 from 1941 until 1952 produced in 281 examples 

(WatchTime Magazine)

Ref 2499 from 1950 until 1985 produced in 349 examples
First model with sapphire crystal

(Antiquorum Auction)

Ref 3970 from 1986 until 2005 produced in approximately 4,000 examples 

(HarrisConor Auction)

Ref 5970 from 2005 until 2010 produced in approximately 2,500 examples 

(minutemachines)

Ref 5270 from 2011

(Patek Philippe)

Honorable mention: Patek ref. 5208 (2011) Perpetual Calendar, Chronograph, Minute repeater. Probably the epitome of the brand sans tourbillon. 
Video of a Thierry Stern interview featuring the watch.

Honorable Mention II: 5204 Perpetual Calendar, split seconds chronograph (there are others in this series like the 5004 but these do not belong in the line of perpetual calendar chronographs discussed in this post).