Thanks for all of that, Tony! If it is indeed Paul Valentine, I think he is super in a duet with Jacqueline McKeever in "We're Not Children" on the OCR of "Oh, Captain!" That's a very fun score with some super orchestrations. His vocal is very sexy, and looking at his bio, he was a ballet dancer, had a relationship with Sally Rand (of bubble dance fame) and was married to Lili St. Cyr, the famous strip tease artist immortalized at the end of "Zip" in "Pal Joey" by Rodgers and Hart! Not sure about Sidney Armus.
I think "Gone With the Wind" may have had a revival in London in more recent years.