King Estmere is an English and Scottish Child ballad and number 60 of 305 ballads collected by Francis James Child.
[1] King Estmere's brother Alder the Younger urges him to marry King Adland's daughter, and suggests that he look at the lady himself, rather than be deceived by any description.
Adler is the son of a magician-woman and enchants King Estmere into the shape of a harper and himself into his boy.
They infiltrate the castle, Alder kills the King of Spain, and the two fight off all his men.
In Bevis: the Story of a Boy by Richard Jefferies King Estmere is the favourite ballad of Bevis.