I once looked up William Richards somewhere on the internet. Some specs for the markings were given & it was stated positively if a gun didn't carry those markings, they didn't build it. Unfortunately I didn't write them down or save them. I was looking up an old W Richards which I have with Birmingham proofs. It didn't meet their criterior so can only surmise that all W Richards guns bearing Birmingham proof didn't originate in the Liverpool plant. Mine is not stamped Liverpool any where, the fact yours is, is a good sign but don't know positively that it is all conclusive. When it arrives post back all its markings.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra