The same thought occurred to me, although I believe the 2.25" x 2.25" format was quite common then. There are no numbers or other identifiers on my negative, but it is cut from a roll, and as you suggest could under ideal circumstances be compared to others from the same roll, if they exist.
Beaton, as many photographers in his era, most likely used a Rolleiflex. But like a bullet from a rifle, small irregularities of the frame edges, positioning of the frame with the negative reference numbers, even characteristics of the lens, can identify sister negatives from the same roll.
And that is also possible. I just can't see the reason for their lack of interest.
But someone else out there might have a greater interest.
One of the links you posted indicated that the image was set up for Beaton. Considering Beaton's standing, I seriously, seriously, seriously doubt there were any other photographers present.
Having his contact sheet would be a telling factor. It's always fascinating to see the contact sheets of those silver-age photographers, seeing how they worked up to their images.


