Crikey, I'm glad that on the two occasions when I've done a floor spot in front of the legendary Will Fly, I've managed to dredge up the lyrics from what I laughingly term my memory. These days I have trouble remembering the songs I've written, let alone anyone else's.
Mind you, I've seen Richard Thompson using printed lyrics on stage, which he explained as the 'choreography - verse 1: raise right foot'.