Here's a reference I had never heard of and which appeared for the 1st time in public at auction last october in New York.
A triple date minute repeater ref 4293, the movement was made in 1943 but only cased in a rather large (for the time) 38mm rose gold case, and sold in 1957. According to Vacheron Constantin archives two models were to be made but only one actually left the ateliers.
It was sold by Christie's New York on Oct 17 for $457,000!
You can click on the scans for a larger view