PATEK PHILIPPE. AN 18K GOLD WRISTWATCH WITH SWEEP CENTRE SECONDS

Reference 565, the first large water-resistant watch featuring a two-piece case with screw back and dust cover, was available with either subsidiary or sweep centre seconds. The first series was launched in 1938 with calibre 12-120, the second with calibre 12-400 in 1950. The centre seconds version featuring a calibre 12 SCi movement started in 1939, replaced by the new calibre 27 SC as of 1949.