I found the definition!

Now all we need is a new one to cover what we really think we are doing! In the same way that Tony Blair has hijacked the Labour party and almost wholly divorced it from its socialist roots (Hmm, interesting, do roots marry and if so how do you divorce them?) and relabelled it "New Labour", I propose "New Folk", partly for the analogy with politics, partly for the analogy with "New Country" (which in the same way that the Lord Privy Seal is neither a Lord a privy or a seal, is neither new nor country, but I still hate it anyway) to include true folk music as defined below, re-arrangements of true folk music with non-traditional instruments (viz. Steeleye Span, and with or without distortion pedals as used by Fariport on "Alison Grimes"), modern acoustic music, semi-plugged same; and semi-plugged versions of established pop songs.

Oh yes, that definition.

Folk Song

In 1954 the International Folk Music Council adopted this definition:-

"Folk music is the product of a musical tradition that. has been evolved through the process of oral transmission. The factors that shape the tradition are: (i) Continuity which links the present with the past; (ii) Variation which springs from the creative impulse of the individual or group; and (iii) Selection by the community, which determines the form or forms in which the music survives.

The term can be applied to music that has been evolved from the rudimentary beginnings by a community uninfluenced by popular music and art music, and it can likewise be applied to the music which has originated with an individual composer and has subsequently been absorbed into the unwritten living tradition of a community.

The term does not cover composed popular music that his been taken over ready-made by a community and remains unchanged, for it is the refashioning-and recreation of the music by the community that gives its folk character."