Maybe its just how the photo was taken, but it appears as thoght the portion where the bell connects to the body is bigger around than the guy's head, whereas the Holton in your picture doesnt appear that large. Again it may just be a matter of an optical illusion or my poor eyes, but that horn looks massive. The guy could be tiny also.
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Also, notice that the guy isn't just holding the horn "on" his lap, but WAY UP on his lap. This is even more surprising given that he does, indeed, look like a smallish fellow. I've never seen anyone hold a tuba the way he's holding this one, reaching THRU the body to hug the bell stack. Bottom line: there isn't much space between the bottom bow and the leadpipe. I wonder if this is monster/giant/whatever Eb.
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Joe Baker, with no theory as to the maker, but pointing out that there were manufacturers back then that we don't hear so much about these days.