Song 67 was one of the airs that appeared in George Wither's (1588-1667) Hymnes and Songs of the Church (London, 1623.) Most of the music in that book is by Orlando Gibbons (1583-1625), so the melody as it appears there may have been selected, adapted, and harmonized by Gibbons. Anyhow, two years previous to its appearance in Hymnes and Songs of the Church, the melody appeared in Edmwnd Prys's (d. 1623) Llyfr y Psalmau (London, 1621.) Since the air was first printed in a Welsh-language book, I take it as a Welsh air.