Here is an overly large flintlock pistol made by ELG in Belgium. This type gun was popular with sailors and is listed in multiple publications as such. It has a large bore barrel and a lanyard wing at the butt. This feature allowed a sailor to attach a cord to his wrist so as not to lose it in the heart of battle on a crowded deck. I believe the wood is walnut? The 'ELG' mark is an early form pre-dating 1830 if I recall. There is a V under a crown mark and an indecipherable stamp to the barrel as well. Note the lack of ramrod, which was deemed pointless as no reloading in the melee of a boarding.
One question I have is whether there is any truth that these pistols were also used by British cavalry in Africa?? It is close to the size of their so-called howdah pistols. Horsemen would also have little opportunity to reload and not need a ramrod.