You are right of course about Richards of Liverpool. The odds are greatly against it being one of his though. As was said above, check the proof marks to see what country of origin. As to the 26in barrel- check the muzzle and choking to form a better opinion regarding whether they may have been cut at some point. Are the steel wedges present between the barrels at the muzzle or is it all lead or solder - stick a pin in it if you can get away with it. (I always forget the name of those little wedges.)
Are the barrels marked laminated steel- pretty common on the cheapo Belgium ones.