Hi, Summerisle, I've not found any other films beyond those on Youtube that I linked to in this thread, sadly.
On a general note, it just occurred to me to have a look on the BBC Genome project* to see if any were listed.
Since posters to this thread who, like me, vaguely remember it being on between the end of Saturday Morning kids shows and the start of Grandstand, I looked at BBC1 schedules for Saturdays in random months between 1977 - 1980. Drawing a number of blanks, suddenly I chanced across this one
http://genome.ch.bbc.co.uk/schedules/bbcone/london/1978-09-09Which isn't that much, but I'm unconvinced BBC1 was showing
The Potters Wheel in 1978! I reckon this would have been one of those films we're after. Shame there's no other information.
Ian
[* Copies of The Radio Times TV & Radio listings have been scanned and digitized, and are available online. Searchable too!
http://genome.ch.bbc.co.uk/]