Slept on it awhile. the frame has become a bug for me. A challenge really. Mainly because for the last year Ive been pouring over the VCC Library finding the history of the two British Club Bikes Ive been restoring. Pulling threads, I've read histories and seen videos and hundreds of bikes. I've been browbeat by several VCC Marque enthusiasts as "that yank with one of our old boys" to get it right if I was doing it at all. These are many times all old guys that cant even ride anymore. Some live amongst their extensive collection of old European bikes.
First, I imagine it very strange that any American bike builder would be using a British BB shell or Head tube at any time. There really is no reason to, specialty shop our not. There is no advantage to the BB Shell. On the finished bike, no-one would know the difference in any way other than to be told. Same goes for the head tube. The headset being unique is one thing, but there is no racing advantage I can see. If you don't want cages around the bearings, simply dont use cages. Add 2 balls and reassemble without cages, Ive done it, it works fine.
Second, if it was in-fact made here in the US, it would have to be before 1938-9' or after 1945. The war was going on in Europe and ships were being sunk. There were no cargo planes. Anything going to and fro was not bicycle parts. In those days, there were very few imported anything, except high end luxury items, used as status. I cant see standard Brompton shells as status.
Third, the direction and placement of the decals actually means something, it was not haphazard or put on at the whimsey of personal choice. Unless of course the owner put them ALL on. If the old guy said his wife put them on, I'll bet she put all of them on.
Fourth, to be serious about where it was made, you just have to have the frame metal tested. 531 and its early and later derivatives are High Manganese types. American bikes were using types of chrome Moly. These are two different directions to get similar results. Reynolds stopped 531 bicycle tube production in 1939 and didn't continue until after the war.
There were actually companies in England like Phillips (Phillips was a parts only company until after the war) that sold entire bike frame kits in a box for someone to fully make their own bikes. This would have been pre and post war only for shipment to the US though. The brazing material was thin brass ribbon, laid in recess' in the tube or lugs, assembled with a flux paste for ease of assembly before heating. Very little if any brass oozed outside the lugs. From what few Ive seen of American lugged bike assembly, the tubes seem to have been fluxed and slid together with the brazing material naturally pulled into the joint with heat from the outside of the joint. Same way copper plumbing is assembled. This leaves a spot or more of brazing material outside the lug on the tubes to be filed down and smoothed out.
My vote is that it is a European frame, later done up with American bits. In 2022 we are too far away from its actual production date for anyone, including a Wastyn family member that didn't actually do the deed, to give provenance unless they have hard copy ephemera.
You may ask the old owner guy if his wife knew of Eileen Sheridan. She would have been a hero to women bicyclists in those days. She set time trials racing records throughout England and did it on a Mercian that was painted and decaled as a Hercules. Hercules sponsored her but she was trained and tested on her own Mercian.
Of course, I may be Bat poop...