As the heir of Patek Philippe’s grand 1941 classic the reference 1518, the Patek Philippe Perpetual Calendar Chronograph ref. 5270 was originally launched at Baselworld 2011 to replace the iconic Patek reference 5970. Some of the main differences between the ref. 5970 and the ref. 5270 includes a bigger case measuring 41 mm vs. 39 mm on the ref. 5970 and an in-house movement powering the ref. 5270 instead of the Lemania 2310-based CH27 calibre in the ref. 5970.