Henry Holland Leigh was an arms merchant in Pemberton, England circa 1876. He was strictly a dealer and not a gun marker. The gun looks to have been refinished. The barrels are later than 1876 and were proofed for black powder in Belgium.

Non Pour Balle translates to Not for Ball. It was an early way of saying the barrels are choked. It was in use from 1878-1898.

I would place this gun in the late 1890's because of the barrels.

Pete