Hi Dan
Interesting pistol. While I can't help with the markings, the pistol does have a definite English flavor to it. The general architecture of the pistol with it's checkered stock and back action percussion lock are common features of many English made pistols sold to private individuals in the 1840-60 period. But the captive ramrod was more in use with the military. And the overall size of the pistol appears a bit large for a belt type pistol of the same style (along with pocket pistols) that were very popular with civilians in Europe during this same period. So, this leads me to believe this pistol may have been made for a British officer under private contract for his personal horse pistol. Which the Military apparently allowed officers to for over a century. It's like a combination of civilian and military features.
Rick