I think it's important to distinguish between "traditional" material and the singing tradition.

The tradition is essentially informal, social and communal - people making their own entertainment, with no real demarcation between performer and audience: everyone was both to some extent. People got songs from all over the place: handed down; broadsides and sheet music; minstrel shows and music hall; later radio and recordings. Anything that caught the fancy was taken on board.

The tradition of people doing their own thing in pubs, family parties, on coach trips etc, was the way that many songs were preserved and disseminated - not all of them "traditional" by any means.

To my mind, half-a-dozen inebriated 40-something ladies in a wine bar bawling out "Simply the Best" or "I will survive" is part of the continuing tradition: Martin Carthy singing traditional material in a concert hall is not.

Concerts, Folk clubs and recordings, with a more or less passive audience being entertained by a "priesthood" are "revival" rather than traditional. Singarounds are on the dividing line between the two, but often feel traditonal to me, especially if there is a bit of discussion or banter and joshing between the songs.