Delighted to find this eight-part adaptation of Asimov's famous trilogy, first broadcast by the BBC in 1973. The episodes are an hour long, which is longer than my preferred listening window, but most of them have plot breaks in the middle. The cast list is impressive, especially for us Doctor Who fans - two Masters, a Davros and Sutekh, not to mention Julian Glover, Maurice Denham, Dinsdale Landen, Angela Pleasance and Prunella Scales. The dominant voice of the second half of the story is the Mule, played very memorably by Wolfe Morris, who was Padmasambhava in The Abominable Snowmen. I had not previously heard of William Eedle, who plays Hari Seldon - there isn't even an IMDB page for him (though there is one for "William Eeedle"). The plotting is not vastly exciting and the talented cast just about manage to make the material work (adopted from the books by Michael Stott, who throws in some comic agricultural scenes for light relief). On the other hand, the background music and sound ambience is very striking - lots of jarring electronic music, which would have sounded very futuristic in 1973 and still sounds suitably futuristic in a 1970s way.
It also is very very clearly one of the inspirations for Douglas Adams' Hitch-Hiker's Guide. I think Adams, as an sf fan, would have appreciated this but also been somewhat disappointed, and the Encyclopedia Galactica (itself of course referenced by Adams) is an obvious source - providing framing description, introduced by its own little twiddle, words spoken by an actor who is otherwise separate from the action. Adams' genius was to take this model and subvert it so memorably. This audio version of the Foundation trilogy, rather more than the original books, is a crucial seed text for Arthur Dent and Zaphod Beeblebrox.