DougR, in the Robert Shaw Chorale's version of "The Cherry Tree Carol" you're referring to, the tenor soloist is Russell Oberlin. The recording is "Christmas Hymns and Carols, Volume II," RCA LM-1711.

Oberlin sang countertenor roles later in the 50s, notably in the Pro Musica Antiqua's PLAY OF DANIEL.

Sharyn, Florence Kopleff is the contralto on this recording, but that's not her on this cut. Robert Shaw made several recordings of Christmas carols with various personnel, released and re-released under various titles, so it must be another session.