Your gun is alot earlier than 1910. Thomas Conway lived and worked in Manchester. From 1803-11 his premises were at 179 Chapel Street. From 1815-28 he was at 3 Market Street. He moved to 4 Blackfriars Street in 1836 and was there until his death in 1852. It appears the exectutors of his estate continued the operation at that location until 1869 before closing, so your gun would be no later than that. He was also a crossbow maker and he retailed Belgian made rook rifles. I'm not an expert but the marks from left to right are: receiver water table, crown over V is the London view mark from 1868 on, Barrel flats: The letters GP interlaced in a cypher surmounted by a lion rampant is the London provisional black powder proof mark used from 1868 on. Next is the London view mark again, the 12 is the bore diameter, and the crown over the intertwined GP is the London definitive black powder proof mark. Since the proof laws requiring those stamps came into effect in 1868 and Conway's business closed in 1869 one of those years would be the build date.You're lucky, it is usually much tougher to pin down the date. A 140 year old gun, very, very cool! It appears from the photo that you have non-rebounding hammers. There are others on this bbs that know more about proof marks than I do so I hope they correct me if I'm wrong.