Very aged is not the same meaning as not cared, but only the leather has been used for a long time. The answer is separation between coating and hide substrate.
This pair is a vintage from British brand K Shoes. The production date is unknown, probably 1970s to 1980s. You can see the extremely delicate leather! Can you tell it is very aged?
The creases of the other foot are relatively thicker, but it is still top notch. Maybe you cannot detect the separation I mentioned, here I show recently made shoes for reference.
This is a pair of CROCKETT & Jones Handgrade. The coating and the leather are more firmly combined.
This pair of Saxone of Scotland made by Loake was made in 1970s or 1980s. The separation is much more obvious.
This pair of John Lobb St. James shoes reflect this phenomenon more clearly. You can’t say John Lobb St. James uses subpar leather.
It seems that American shoe factories have better performance. The separation on this pair of HANOVER Imperial made in 1980s or 1990s is not as obvious as British opponents.
This pair of Nettleton made in 1980s in the United States has unrivaled leather performance.
Summary
Many of us buy stitched shoes for their durability, and fantasy that you can resole so many times as long as the upper is sound. But what happens if the leather just ages? Now you know the answer. Can you accept this performance and still resole them?