I am looking the lyrics.

These is a Borodin piece which, prior to 1969, had lyrics which were used in middle school chorale classes.

The lyrics aren’t “Stranger in Paradise”.

I believe the first line was “Come with us to the steppes … “

Despite my “mad Internet search skills” I’ve been unable to surface the lyric.

https://www.youtube.com/watch?v=5zrgQ_Gdsms

https://youtu.be/jgqvWVXMaPw?t=951
You can hear it a little better in this second clip. From 15:50, in case the timestamp doesn't work.

I've been trying to identify the angelic-sounding choral piece heard faintly in the background of this scene.
Please note: It is not part of the film's score/soundtrack, and does not appear to be from Michael Nyman, the composer of the film's main score.

Incidentally, it can also be heard in "A TV Dante", also by Greenaway, also starring John Gielgud, and also playing exclusively during a sequence in which he is speaking over it.

If anyone can identify this music, I will be eternally grateful to them. I've tried every other avenue short of tracking down Peter Greenaway and asking him if he remembers the name of the sacred music he dropped a few seconds of into the background of a movie he made nearly four decades ago.

https://youtu.be/WKtzxWR9Zt4