Not so, it turns out, since his image (in the 1993 expanded edition, TOLKIEN PORTRAITURE) includes the original caption from its apparent first publication (wherever that was), while Barratt's reproduction has its own caption ("Professor J. R. T. Tolkien, author of The Lord of the Rings, in his study at Merton College, Oxford"). And, just for the record, Barratt in his Photograph acknowledgments credits BBC Hutton Picture Library for this image.
By the way, while searching for something else today on WorldCat, to my surprise I discovered a copy of Dr. Blackwelder's never-published book listed (the 1993 version, I think), w. myself given as one of the assisting authors:
This turns out to be Marquette's copy, wh. Dr. Blackwelder would have given them along with the rest of his bequest. So I assume any researcher who visits the Special Collection there shd be able to consult it for themselves. Just don't be disappointed by the poor quality of the photocopy reproductions of the photos and drawings; the pictures are recognizable but much of the detail is lost, since this was just a working project, not anything finalized for publication.
Still, it's a handy referent, and shows how interesting a full-fledged book on the topic would be. I'd love to see a book someday similar to THE PORTRAITS AND DAGUERREOTYPES OF EDGAR ALLAN POE (by Michael J. Deas ), which reproduces, in sequence, every known surviving photo or contemporary painting of Poe.* But I don't think we'll be getting one anytime soon.
In any case, as I said in my most recent Simon Tolkien post -- hooray! Today we get a new Tolkien photo!
*a collection made all the more interesting by the little-known fact that Poe only grew his moustache the last four years of his life; before that he'd had sideburns.