From the Christmas Carol Songbook:
cantorion.org/ ... tmas-Carol-Songbook-Voice-SATB
"What Child Is This?" is a Christmas carol whose lyrics were written by William Chatterton Dix, in 1865. At the time of composing the carol, Dix worked as an insurance company manager and had been struck by a severe illness. While recovering, he underwent a spiritual renewal that led him to write several hymns, including lyrics to this carol that was subsequently set to the tune of "Greensleeves", a traditional English folk song. Although it was written in Great Britain, the carol is more popular in the United States than in its country of origin today.
The above text from the Wikipedia article "What Child Is This?" text is available under CC BY-SA 3.0.

Greensleeves est une chanson anglaise traditionnelle écrite en l'honneur d'une « dame aux manches vertes » . D'après une légende populaire, elle aurait été composée par le roi Henri VIII (1491-1547) en l'honneur d'Anne Boleyn. Elle est fondée sur le passamezzo antico Passamezzo#Passamezzo antico ou la Romanesca très voisine. , une basse obstinée ou progression d'accords populaire pendant la Renaissance italienne et connue dans toute l'Europe au XVIe siècle.
The above text from the Wikipedia article "Greensleeves" text is available under CC BY-SA 3.0.