Guest - you have "found 14 disks in all and just one has a "stereo" stamp to it." They're from series 1. As you know the disks would be paired together. So you have a mixture of A and B sides of the first 13 episodes. I think the recordings would have been in stereo, but the eventual disks would have been manufactured as mono.

Its a shame the discs did not come with inserts - these are collectible too.

Its interesting the detail re: Decca. The discs should have the matrix number somewhere near the runout groove, or maybe on the edge. There are catalogues of these. The folk at the LOC's "Association for Recorded Sound Discussion List" might have access to these.

Re: your other discs, a list would be great. Although most trans discs are documented for such programmes. The BBC has a huge collection in Bristol. They are gradually being re-aired on R4X. One Keith Wickham - as a hobby - restores such (and home-taped recordings) for BBC R4X. He even uses home-taped recordings to splice in missing cuts to trans discs. As you might know trans discs were always approx. 25 mins long to leave room for overseas commercial stations to air commercials.

Incidentally with regards to LFSC trans discs these are invariable less than 25 mins per side (i.e. less than 50 mins per programme). We have yet to identify where the cuts were made from the original 60 minute programmes as aired and the commensurate trans disc versions. There are no surviving recordings of the original aired programmes.   

As an aside there is a Facebook Group for collectors of BBC trans discs. Ex-Beeb staff are active on it and have great stories to tell of the old days.