Author: The words of this song was written by William Chatterton Dix (1837 - 1898), a hymn writer who also wrote carols. The three verses were actually taken from Dix' poem "The Manger Throne" and harmonized with the famous melody known as "Greensleeves." The said melody was a traditional English melody that was popularly used in many texts during the 14th century.
Interesting Fact: The carol "What Child Is This?" was first published on Christmas Carols New and Old around 1867 and edited by Bramley/Stainer.
What Child is this who, laid to rest
On Mary’s lap is sleeping?
Whom angels greet with anthems sweet,
While shepherds watch are keeping?
This, this is Christ the King,
Whom shepherds guard and angels sing;
Haste, haste, to bring Him laud,
The Babe, the Son of Mary.
Music Sheet: Arrangements by Sally DeFord: