The thing is of course that much 'folk' music and folksong has beards and sandals.

You know how the guy who wrote A Man For All seasons - Robert Something said he wanted to avoid 'gadzookery' in the language. In folksong - even modern songs written 'in the tradition' - there is often a certain reaching out to archaicism in the language.

The garb is really just showing a unified approach. I was watching O'Hooley and Tidow the other night - I was thinking the collarless shirts and waistcoats were a sort of nod in the direction 19th century artisans.