With reference to earlier messages in this thread and culling relevant info from them, I have created a Wikipedia page for Marian here: https://en.wikipedia.org/wiki/Marian_Henderson . Further input / corrections etc. are welcome (noting that all WP content must ostensibly be sourceable i.e. published in some reputable form - not a blog or discussion forum). I will add a photo from one of her album/EP release covers in a little while (while not public domain, this is deemed "fair use" where no other alternative is available).
Regards - Tony