The lock was made by Goulcher, but the gun is likely the product of a local gun maker. The trigger guard, set trigger, patch box and butt plate all appear to be trade products, made in factories and sold by gunsmith supply houses (sort of like Brownell's today). The hammer does not meet the nipple squarely, yet the hammer appears to be original, suggesting that the barrel or at least the drum is not original. I have the feeling, as Jim Watson suggests, that it is a gun made up from at least two other rifles.
Jim