Re: Henry Elwell Dbl BBL Shotgun Value
Welcome to TFF.
Photos would better confirm what you have, but it's probably a percussion double barrel.
Boothroyd lists Henry Elwell as a gunmaker in Birmingham 1838-1857, with added remark: "Marked guns London."
I don't know how anyone could possibly determine that only three guns had his name on the locks, but rarity does not necessarily mean higher value, and such guns have moderate collector interest.
If you can post a clear photo of the barrel rib marking, perhaps we can determine what it is that looks like "Real Time"