Where does this recording come from? Murder on the Links audiobook

I found this unabridged reading of the book "Murder on the Links" by Agatha Christie. It was uploaded in 2023 on Spotify by a "John McCormick". The original recording is decidedly vintage though. I am pretty sure he took it from some other source, probably older than the 80s.

I cannot, for the life of me, find the original source though. Maybe a really old, limited distribution on cassette? a "book for the blind" recording? maybe from a really old library archive? I have spent the better part of today trying to find the original.

The first upload on Spotify in 12 parts: https://open.spotify.com/show/7iEKbAmFF7rB4Lsf4B2vlS (missing Episode 1 for some reason)

Another Spotify Upload in 1 part and under a different title: https://open.spotify.com/episode/33u9X94DOznHzjMihHfU5l?si=c991066b6a3549f6

The runtime is about 7 hours and 25 minutes

Any leads?

Thank you in advance!