You've gotten good counsel here, my take is that it's about a $3500 - $4000 gun. It's a long way from a best gun (wood/metal fit; not stocked to the fences; visible third fastener; light engraving), judging by just the pictures alone. Not mentioned is barrel wall thickness, barrels on face, ribs intact, etc. Original condition in a British gun is not a factor - key is current condition (though the refinishing issue is a question of wear not value).