My guess with regard to those writing such statements and referring to "sessions" they play in, that these are predominantly "tune sessions" in which case I am not at all surprised that there is a high percentage of traditional material played.

Your guess would be wrong. Most sessions are predominantly about recently composed tunes in the traditional idiom (or an idiom recognizably derived from it).


"House Concerts" are becoming more common I have been to quite a few but there you tend to meet the same people time and time again and all seem to be very much of an age, I've certainly seen no evidence of "intergenerational communication".

I was talking about participatory events, not concerts. (I've been to three house concerts in my life and I was playing at two of them).