We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "David WE Roberts"
saying something like:

Read the refs in the headers and retrieve the post.

Ah...O.K. I can see a series of references in the posts which get longer
further down the thread.
So I presume that the first one is the original post

That's it.
..
However I have no idea how to use this reference to retrieve the original
post.

In Agent, I double click on the ref and Agent goes and gets it with a
bit of jumping about.

My news reader is Windows Mail so is not 'feature rich'.

Possibly not this way, true.