I've now received a further e mail from LCA, still in response to my first e mail, as follows:-
I believe the drawing Paul refers to, is the one shown below, which bears L.C.Wyon's signature. Compared to the one in Lot 1189, I'd say it is the same signature, so the document appears to be authentic.
This coin is a TB/TB example. Even though the reverse teeth have a somewhat rounded appearance, they are indeed toothed in reality. On a real BB example the beads are closer to the inner ring, not the outer rim. There is also a differance in the Bead count, though I don't recall what it is. Every coin dealer here in the US has a example like yours marked as a Mule, which is incorrect. I have a example I purchased from Michael Freeman on my website, if you care to see a authentic example.
I'd go for a minting flaw. A defective flan with lamination will transfer the design to the layer below the lamination break, so you would still see some semblance of what it should be like, even with the missing top skin.
It looks similar but there are differences.
The inscription on the bottom of the box could be interpreted in two ways.
Firstly, it could just be a note that records what took place. The coin was given to someone by L. C..Wyon.
or
It is as assumed, a note written in his hand. Personally I think the signature on the portrait doesn't match enough to prove conclusively
The surfaces of the REV look as though they have been spray painted, it might just be the angle of the picture but they do look a little rough. Does the auction where you bought these do coins normally? Would they know a genuine American $5 from a fake one?