While it could have applied to Justin Hayward’s vocals in “Nights in White Satin” it was - depending on how you look at it - the end of that song after that song often called (and often omitted) “Late Lament” (as 2 bits pointed out just above) that Mike Pinder recites and which FM radio used to play.
That’s the part I love the most. They never sound the same each time, and the wow and flutter, to me, adds a character missing, and not dulpicatable, from any synth or sampler. It always sounds like a weak station heard on an analog radio from the other room, fading in and out of reality. Sad, depressing, “moody”, if you will.
Now this isn’t a “digital music is cold and perfect” thing, if I were in a band I’d have the best, modern synths and samplers. But the mellotron is…special. My perfect band has a mellotron, a theremin and a glass harmonica.