Grandalf: The cache has definitely vanished, most likely removed as rubbish by active Council gardeners who have cleared away most of the material used to hide the cachebox.
So I'm archiving this cache, with the intention of using the same type of puzzle at another site.
In my last posting, I asked the previous three DNFs to email me the coordinates they had solved. Only one did so, and they were correct. So I'm permitting them to log the cache to be the last finder.
Cheers from Grandalf