Patek Philippe produced a total of 281 examples of the Ref. 1518, beginning in 1941.
A similar example is illustrated in Patek Philippe Wristwatches by Martin Huber & Alan Banbery, 2nd edition, pp. 303.
This watch is accompanied by a Patek Philippe Extract from the Archives confirming production in 1950 and its subsequent sale on December 19th, 1952.