Further,

I've also seen this sort of thing at festivals such as Auchtermuchty and in down in The Borders. Generally, it's in areas where the Fiddle/Accordion scene is quite strong.

Sometimes, the above and the more traditional and/or folky music can complement each other. Sometimes they might collide, of course.

Of course, you will inevitably get a cross over or influence from the music(s) of the area. e.g. some festivals have lots of piping, others Gaelic song and so on.
So, I wouldn't really expect to encounter too many sessions and singarounds which are completely faithful to that of the folk club scene past or present.