Independent label: Folk label from Bromley, Kent. Blackthorne seems to have operated from 1976-88. It was owned by those veterans of the British Folk scene Ewan MacColl and Peggy Seeger, and its products all appear to have been solo or duo recordings by them. It dealt mainly in LPs, but there were at least two singles, both of them in 1977.  Peggy Seeger's, 'Housewife's Alphabet' (BR-20525) was the first; she was joined by Ewan MacColl for the second, 'Parliamentary Polka' (BR-20535), Thanks to Robert Lyons For The Info.

77 Seeger Peggy  Housewife's Alphabet BLACKTHORNE BR 20525
77 Seeger Peggy  Parliamentary Polka BLACKTHORNE BR 20535