Barriers to continuing to sing these songs is perhaps the pc brigade which might take exception to such revelations to the young people singing or even knowing of what went on

In my experience "the PC brigade" are the young people - there's a generation that's grown up, not objecting to racist & sexist language, but actually not hearing it at all (except when used aggressively). So it's understandable that they don't want to start hearing it when they come to a folk session.

I don't think we should edit songs to avoid offence, though - although there are some songs that we can stop singing at all, including some traditional songs.