I ask (yet again) about the place of tunes in all this.

Some of the tune titles which are reasonably modern compositions (within the last 30 years) and which get played regularly at sessions - whether you like them or not - are Pete James's "Horizonto", Jay Ungar's "Ashokan Farewell", Tom Anderson's "Da Slockit Light", Joan MacDonald Boes's "The Sweetness of Mary" and quite a few others. Not in the slightest way unknown in origin - but quietly slipping into a 'music traditionally played' category.

Going even further back in time - to look at precedents for such incorporation of modern composition - we have Carolan...