Do either of the locks or the top rib have any words engraved on them? Your photos of the lockplates are not close enough for me to be able to read. British guns are often engraved with name of who sold the gun, which many times is not who actually made the gun. It looks to be a high grade hammer gun, Whitworth barrels are some indication of the level of quality, which I believe to be very high.
Value is subjective....depending heavily on condition. The outside of the gun looks to be in pretty good conditon from the photos, the barrel condition will greatly affect value. Rough guess, assuming good bores would be about 3K + or - a little bit. Good luck,
Steve


Firearms imports, consignments


[Linked Image from i.imgur.com]