>>>>>wassail songs, work songs, local carols, drinking songs<<<<<

Apart from local carols which are well-documented, which of the other 3 have examples of being sung in any other way other than by a lead singer singing the verses? Other than the examples already given here I might add. Even chanteys were always as far as we know a solo lead singer. Where we have recordings of strong traditional pub sings (East Anglia in particular) the rule was 'one singer, one song' with the others joining in the chorus. Bob Roberts was sometimes present at these as a young man, with his melodeon, but he only used it to accompany step-dancing and his own songs.