And consider the mix of traditional and contemporary songs which would appear in 'Sing Out', & its UK equivalent 'Sing' {edited by my good [but certainly Marxist] friend, the late Eric Winter}. Not all the traditional songs, certainly, would be appropriate to the 'class struggle' & such; but I think you will find that a fair proportion would be such as, eg The Durham Strike and so forth; or mine-disaster songs like The Blantyre Explosion. All part of the rich tapestry of folklore, of course; but capable of tendentious selection even so, perhaps?