I brought a "Wallhanger" double barrel muzzle loading shotgun today. It's marked Hewson on the locks and has London on the top rib. There are three proof marks on one barrel and none on the other. The barrels look to be steel - not Damascus or twist, and are shorter than I'd expect for a muzzle loading shotgun.
Photobucket is not cooperative this evening and the pictures above is not of the gun I bought but the gun I bought is in rougher condition and has less engraving.
I'll update with pictures of the actual gun when I can get them uploaded.
Any information on the origin of this gun and appropriate date it was made would be appreciated.