Posted by Michael Gilligan on 14/04/2020 09:28:39:
.. which seems a little odd; because clicking ‘parent directory’ then takes you to the home page [where there appears to be no link available]
That is my point. You know where to look so you can confirm it is still there. But if you did not know, how would you go about finding it?
It is only through someone's chance remembering of your old, old posting that it has been found.
Try and find your original post as if you did not know it was there. In theory 'percival marshall site:model-engineer.co.uk' should eventually find it but you have to sift a lot of material.
Try and go at finding the audio file cold using the best Google-fu you have. If the file just sits on a server with no other page linking to it, it is almost impossible to find.
I suspect it used to be pointed to from the neme-s homepage, which is how you found it a long time ago, but that the neme-s page has been edited and the link removed.