The name of the estate comes from its geographical location on the Cos hill and the name of François Labory, who was the first owner until 1845. Mr. d'Estournel then acquired it before selling it again to an English banker, Charles Martyns in 1852.
The property was finally taken over by George Weber in the 1930's, who bequeathed it to his daughter and son-in-law, François Audoy in 1959. In 1971, the couple acquired the neighbouring estate, Château Andron Blanquet. Their sons worked with them on the two estates for a few years and then the elder son, Bernard, took over the running of the properties.