Well, I had an opportunity to examine these guns and measure barrels, etc and I wound up buying the William Moore & Grey which is going to get a real good professional cleaning inside and out, a couple of barrel dents removed and a small area on the barrels touched up. It's pretty dirty and gummy but it has never been refinished and retains most case colours, barrel brown, excellent checkering and perfect engraving, although the stock finish is thin and gummy in places so it will need attention. As suspected, it is a black powder proofed 2 1/2" gun with barrel walls near minimum thickness having been rebored to remove pits. It locks up solid as new, really handles nicely and will make a great black powder shooter. Research confirms it was made in 1878 and yes it's a bar in wood and with double Purdy underbites and dolls head. Typical of the era it also has one or more very interesting patents applied including one I've never seen before.
The Charles Boswell turned out to be a very nice gun as well although with considerably more wear than the Moore & Grey. It is a much later gun, around 1898, a live pigeon gun with original Nitro Proofed 2 3/4" chambers, broad pigeon rib, side clips, very attractive and usable with standard modern 2 3/4" ammo, nice. Really good hammer guns with Nitro Proofed 2 3/4" damascus barrels by really good makers are rare as rocking horse poop. I really liked this feature and was tempted but the beauty of the Moore & Grey won out. It has also been purchased.
The Charles Hellis 16 is of high grade but has had a rough life. Again unusual, it is a well engraved A&D boxlock 16 gauge with 30" barrels. For someone willing to extend some love and spend some time and money this will make a beautiful and unusual gun by a very good London maker. It may still be available.