A lot of trad songs are politically incorrect in one way or another; if you wanted to be picky, you could object to any number of ballads. The advice given so far seems right to me: sing these songs if they are appropriate for the audience, and if the words are as clearly objectionable as those of "Sir Hugh" say a few words of explanation first. Punkers and rappers seem to get away with saying anything at all; we shouldn't feel intimidated about traditional material.

Stephen