"The Whummil Bore" (Roud 3722, Child 27) is an English-language folk song.
A whummil is a tool for drilling holes.
The narrator served the king seven years and "saw his daughter only once"—meaning saw her naked, through a whummil bore.
[1] "Hind Horn" appears to contain a stanza from it.
[2] This is recorded on the Steeleye Span 2006 album Bloody Men.