Maybe rebored or maybe had the chambers opened. Those are the normal 1-1/4 oz proofs I believe. Maybe they are simply the original proofs.
I am not sure as to the concern. You can submit a gun to any proof house you want. My understanding was that B'ham was cheaper. The gun could have been remarketed and originally proofed in B'ham.
My guess is that it is a Birmingham gun bought in the white and finished at Evan Williams. I have a similar H&H. H&H bought in guns to finish; guns to regulate/adjust/finish; and built in house. All were marked differently. Evans, as I understand it, was not a gun builder or mechanic ran the front counter for Purdey and H&H. I don't believe he actually built guns but purchased the finest available guns and had them finished by outsourced providers of services.
