Two (and possibly three) versions of this triple chant are found in the Cambridge University Library archive: 

• The earliest version (197-?) appears to be the triple chant for Psalm 127. ATBB & organ in C major.
• Then MS.Tranchell.3.68, the version for SATB & organ in E flat major. This version might be assumed to date from the period 1982-1989 when the Gonville & Caius College Choir added a soprano line.
• The archive also records MS.Tranchell.3.67 "For ATBB & organ in E minor [sic]. Photocopy of MS.Tranchell.4.86 with holograph revisions". Cataloguing error seems likely here, but we have not had a chance to check.