Sorry I got on this one late. A few years ago when I was in the throes of research for the Kindig Collection book, I spent a fair amount of time looking at pistols, including the famous Zorger pistols at Winterthur (which Kindig found).I've handled the pair and found the elaborate, unmarked, silver sideplate (not the same as Henry design) was not up to the high standard of English pistol silver side plates. In fact, the surface itself had what could be described as tiny holes, which indicate inferior castings or perhaps re-casting. Also, the Winterthur "object report" indicated that the silver content was below the British sterling standard at the time of supposed build.
The J. P. Beck pistol in our Lancaster Long Rifle Exhibit at Landis Valley Museum in 2012, also contained an unmarked silver side plate and a grotesque butt cap. It too had pockmarked silver. The Jacob Sees pair in the Exhibit did not have a sideplate, but its silver trigger guard of English design appeared of better quality, but the butt plate was a plain simple design, which makes me believe the trigger guards were from another pair. I'm suspicious of any British sideplate or grotesque butt design seen on American pistols, when claimed to be made by an American gunsmith.
I've seen this disparity of quality between English and American silver on numerous firearms and frankly, on other silver. I do not recall the source, Neal, Dixon or maybe, Blackmore, but I've read that the British Silver (Goldsmiths) Guild allowed "inferior" gun hardware to be exported - without silver marks, since it was considered inferior by Guild standards.
The sideplate panolpy design on the Henry pair is perhaps the most often seen design on British firearms, and although I can't see the closeup here that well, it too appears to have a rough surface, as does another photo I've seen of this pair. I suppose I'm suggesting Henry may have either imported the silver or re-cast from another casting. And, Scott,- I'm sure I've seen this basic design on other American pistols/guns-I'll search again. By the way, this pair of pistols is now in the Philadephia History Museum at Atwater Kent, Philadelphia, I just never got around to seeing it. Someone should handle the pair and determine the level of quality of the Henry silver sideplate, before concluding Henry made it from scratch.
Another thought - how many times have you seen these British sideplate designs on American long guns? The Brits used them on high-end fowlers. This subject of American gunsmiths using English parts, or for that matter German or French, is long overdue due for a good informative book.
Patrick Hornberger