Partly answering my own questions -
I've been able to locate a copy of EKL 27, which contains
some information, viz:
"Coop was born in Washington, North Carolina, in 1921. He is the youngest of eleven children. At sixteen he moved to Boston where he entered high school. At twenty he enrolled as a sociology major and a music minor at Hampton Institute. Coop became a counselor at the Wiltwyck School, a New York State institution which is famous for the splendid care it gives emotionally disturbed children. He found that the children responded extremely well to folksongs and consequently he became even more engrossed in searching out and performing new material, often learning different versions of songs already familiar to him from the youngsters in his care. It was while at Wiltwyck that Coop was given the important role of the sympathetic counselor in the widely acclaimed documentary film THE QUIET ONE.
Coop left Wiltwyck in 1950 and has since performed widely in person and on radio. This is his first record for ELEKTRA."
Sadly, this confirms the screen credit mentioned in my original note - IMDB stating that he died 6 December 1974.
Additional information: he performed at NEWPORT in the late 1960's
(1967 or 1968?). A note (on Mudcat) listing the contents of the
Newport Folk Festival Songbook states "Water is Wide, Clarence Cooper".
Concerning the LIMELIGHT record: I've just listened to it again,
and now having heard the Elektra album think that he does NOT perform on that album. Any other opinions?
Anyone having TARRIERS albums please let me know what he performs, which albums. Nice baritone voice....
Also, did anyone know him in those heady NY 1950-1960's folk days - perhaps you could provide recollections.
Thanks!
Best wishes, Thomas.