Dazbo, I see your point re Cambridge Folk Festival but I don't think folk is the poor relation of jazz anymore. In Britain, folk outsells jazz by, oh, all of about 0.2%, but that's significant because of the size of markets we're talking about (though oh, how I hate talking about "markets" at all).

Yes, traditional music should be cherished, but a living tradition develops. Living in NE England makes you aware of this: the region's had its fair share of eclectic blending from way back through the centuries - the Northumbrian pipes are probably derived from the French musette; James Hill who wrote so many wonderful Tyneside hornpipes was Scottish; etc, etc. I think the occasional adoption of jazz phrasing or harmony is just part of that process (another North Easterner, Kathryn Tickell, does this a lot of course). It seems to me that the best examples of eclecticism often come from those performers who also excel at more "pure" traditional music.