Lost Opera

Hopefully there are some opera lovers out there.

I'm trying to replace a recording I made in the 1970s (?), but which was somehow lost. I have searched everywhere I can think of to obtain a copy of the production and have come up with zilch. If anyone can help, please let me know.

Known details:
The Marriage of Figaro (1970s) - BBC TV production
Sung in English (Edward J. Dent translation)

Figaro - Thomas Allen
Susannah - Norma Burrowes
Countess - Elizabeth Harwood
Cherubino - Frederica von Stade
Dr. Bartolo - Derek Hammond-Stroud  
Basilio -?
Count - ?
Marcellina - ?
Gardener - Ian Wallace

Conductor - possibly Sir Charles Mackerras

I'll add more detail if and when.

Thanks.