Hi Larry,
Some times, when industries change, lots of companies go out of business, and are sold for almost nothing. In those cases, people with some cash can acquire famous brand names for very little.
Henry Rieger was a good example of this, buying a slew of companies (their names really) in the early 20th century.
The end of WWII was such a time, when people needed money to rebuild their home, and not to go hunting.
I suspect that V-C went on such a spree and cheaply acquired these brands that were quite important before the war.
Jean Breuil was 75 years old in 1951, and probably was the heart and soul of his operation. After his departure, his business could have unraveled.
The situation in the UK was similar with major concentration at the same time, and the unraveling of dozens of well-known firms (such as Woodward).
Best regards,
WC-