With such a large number of surplus Sniders in the military at the time of the changeover in the middle to late 1870s, Blakemore, already a well-known maker, began assembling guns like this for the Raj, where Snider ammunition was readily available for 'leisure' purposes. Your gun may have been made for such a market - Rhodda of Calcutta made hundred of conversions, and re-assembled guns.
The use of a gun like this in UK was very limited - no large game, unless you count the Scottish Red Stag. I blame the Romans, me.
tac