Double chant for Psalm 75 in A major, D major or E flat major, and Psalm 102 in B flat major

Four versions of this double chant are known. Three are found in the Cambridge University Library archive: 

• The earliest version (undated) appears to be the double chant for Psalm 75. ATBB & organ in A major.
• Then we have double chant for Psalm 75. SATBrB & organ in D major and the version for SATBrB & organ in E flat major. These versions might be assumed to date from the period 1982-1989 when the Gonville & Caius College Choir added a soprano line.