Not a single unaccompanied traditional song (whether from a folksinger or folksong singer).
No Martin Carthy
No June Tabor
No Young Tradition (nor Bellamy, less to my taste but very influential)
No Jon Loomes
No Brian Peters
No Bert Lloyd
No Ewan MacColl (I don't like his singing but he was somewhat important)
No John Kirkpatrick (surely the dominant squeezer of our times)
No Nic Jones
No Copper Family
No Watersons

"Ultimate Folk Playlist" my arse.