I bought one bottle of Cahors - Clos de Gamot 1937 and one 1914 at auction at least 20 years ago, and they have been properly stored. The
1937 had a sound, but somewhat soft cork, and the fill was barely below the neck. These wines were relative bargins back then compared with more popular Bordeaux wines of about the same age.
The color is still rather deep scarlet with a bit of brick around the edges. There is no hint of oxidation. There is plenty of acid. There still is a bit of dryish tannin. This must have been a black, tannic monster when it was young. There is good fruit - mainly of a plum character with perhaps hints of sour cherry. There is a faint hint of clean straw that I often have found in very old wines. The wine held up very well after opening.
There was not much sediment, but it was black as india ink. I am guessing that this wine was kept in cask a long time before bottling and much of the sediment deposited in the cask. Long barrel aging once was fairly common in some regions of France. Even fairly recent vintages of the Spanish wine Vega Sicilia Unico were aged in Bordeaux barricas for no less than 10 years.
Based on this tasting, I have decided to keep the 1914 for 10 more years until it is 100 years old. I examined the bottle, and it appears to be in good condition with no leakage.