I'm thinking that a customer would walk into an obscure sporting establishment, currently long out of business, and order a gun from them. They, this particular sporting establishment, would contact W & C Scott or AA Brown or a host of others to have it built with that particular establishments name engraved on the barrels?
So what we have now is a bunch of English masterpieces running around with obscure sports shops name's stamped on the barrels in plain sight. But somewhere, in some obscure place, there is a small stamp that identifies the maker of said masterpiece.
Interesting trade methods.