Corpus Christi Carol is a Middle or Early Modern English hymn (or carol), first found by an apprentice grocer named Richard Hill in a manuscript written around 1504. The original writer of the carol remains anonymous. The earliest surviving record of the piece preserves only the lyrics and is untitled. It has survived in altered form in the folk tradition as the Christmas carol Down In Yon Forest.
The structure of the carol is six stanzas, each with rhyming couplets. The tense changes in the fourth stanza from past to present continuous.
One hypothesis about the meaning of the carol is that it is concerned with the legend of the Holy Grail. In Arthurian traditions of the Grail story, the Fisher King is the knight who is the Grail's protector, and whose legs are perpetually wounded. When he is wounded his kingdom suffers and becomes a wasteland. This would explain the reference to "an orchard brown".
One recent interpretation is that it was composed about the execution of Anne Boleyn, wife of Henry VIII, whose badge was a falcon.
Peter Warlock used the carol in composition and applied it to those that died at war in 1919.
Benjamin Britten used it in the fifth variation of A Boy was Born (Choral Variations For Mixed Voices), Opus 3, in 1933. The text was combined with Christina Rossetti's In the Bleak Midwinter.
Harrison Birtwistle combined it with 'O my deir hert, young Jesus sweit' by James, John and Robert Wedderburn in his Monody for Corpus Christi, for soprano, flute, violin and horn, in 1959.