Interesting converted pistol.

[Rick]

This pistol could be a Persian copy of an English pistol ; M.O.P. was used as a decorative material in Persia .

This could also be either Afghan or Indian work .
Do we know for sure that this is an original English pistol or an Eastern copy of which there are many .

This Pistol could also be a composite piece from 20th C. India ; possibly an old piece dolled up to make it more attractive to the "Ones who travel for pleasure" have you checked for machine made parts such as screws ?

{added}

Another hint as to its origin may be the vestigial ramrod socket which to my eye looks to be too short to adequately service the barrel . If I recall correctly many Eastern cultures carried the rammer as a separate accessory on their person rather than attached to the pistol in the European manner .