The point was he knew some of his songs were of a considerable age and others were not.

Interstingly Jim there is a passage in "Travellers Songs from England and Scotland".....P19)that backs this up very well.

....we would like to comment on the fact the certain songs within the repertoire of a creative singer were not given the same treatment as other songs. For instance both Mr. Ridley and Mrs Hughes sang "Twenty One Years" wth almost none of their characteristic improvisation. "Green grows the Laurel" was rarely decorated by any of our singers. These are semi-popular songs sometimes learned from recordings or from the radio, songs which are understood to exist in one version only. They seem to remain unchanged, unaffected by a singer's creativity, although they are widely sung.