I just found this: https://www.youtube.com/watch?v=JlGyCifcoJg
Isla singing this very melody version, from 1958 LP "I still love him "(with Ewan MacColl).

And IMDB indeed confirms Isla was the folk music advisor of Far from the Madding crowd from 1967. However she doesn't seem to have sung this particular song, in the soundtrack Trevor Lucas is listed to sing "I sowed the seeds of love" - but it would of course be IC's version. Cool.

Maria O