This submission may be a bit of a stretch, but examination of the Gilbert New Haven AF catalogs from 1939-41 and 1946-49 contain an illustration of a No. 247 (and No. 249) tunnel of a later style with two bumps on the top with a more simple design than the ones beautifully posted above. Offered here because it is interesting, arguably relevant, and pretty darned tough to find is a No. 247 (circa 1946) also made of hand-painted pressed cardboard and paper.
Respectfully,
Bob