A1) foxtrot, almost certainly Harry Bidgoods Dance Band.
The central core of these Unbreakable types have several layers of thin paper/card like material completely encapsulated in a thin covering of fine shellac.
Many customers obtained their Duophone UB records by mail order.
So that there is no misunderstanding, I only have one copy of J.F. 19. The hidden image was photographed in natural light - the other two images were taken under a LED light-box.
Thanks to interested parties. As current owner, I can add that the 'paste over' was expertly positioned with some force in attachment. In appearance, it has aged sympatheticly with the underlying label which is of course English. Closer examination reveals that witness marks underneath align perfectly with both of the labels. Markings in the dead wax are typically English HMV, but the shellac does appear richer and darker than any others I've seen from this period. It does play exceptionally well. Lastly, the Missouri Moan side has been played much more than Ozark side.