Starting at the focal point of the railways, proceed uphill in a vaguely easterly direction. About 20m along, you'll find a telegraph pole marked "8A": take the lefthand (flatter) track up. Keep walking until you reach a break in the trees, through which is a superb view across Cheltenham to the Malverns.
The cache is a little further along, hidden at ground level in a dip adjacent to the ruins of a NE-SW segment of the wall that separated the common land of Leckhampton Hill and Charlton Kings. The cache container is not in the wall: please don't rearrange the rubble.
Once you've found the cache, walk a few steps East along the line of the ruined wall, then take the narrow path (not the main path that you left earlier) that snakes up a small mound ahead of you. In 30 seconds you'll be on top of Charlton Kings Crags, with an even more impressive vista stretching out ahead of you!
Cheltenham Borough Council have provided the following information about this historical feature of the hill:
The wall is the divide between Charlton Kings Common and Leckhampton Hill Common. We had an idea that there was a divide but because of the undergrowth and the tree re-growth it had been hidden for years. From what I can gather boundary walls were put up when people couldn't read or write and therefore the best way for people to understand/know where the boundaries lay was to put a physical structure in place such as a wall. We are hoping to rebuild this particular section as it will be a great landmark, but I don't know why it fell into disrepair. We purchased Leckhampton Hill Common in 1925 after it was quarried and I think Charlton Kings Parish Council bequeathed CKC to us at a later date but it seems the wall was left hidden until we de-scrubbed the area.
For a fascinating review of the various biological, geological and historical features of the site, the reader is referred to sections of the Leckhampton Hill and Charlton Kings Common management plan [pdf].