It would probably help to establish a definitive list of pre-1980s folk programmes. Appended could be the known years of existence, i.e. date of first edition v.v. date of last edition.

As a start there is:

(London) Folk Song Cellar
Folk & Country British Style
Country Meets Folk
Folk on 2
Friday's Folk
Folk 76
Folk 78
Folk 77 (presumably)
Folkweave

...

For holdings I would suggest setting up a spreadsheet on Google docs to which anyone could append details. Or maybe use a Yahoo groups database - perhaps TradTunes?