You know this might be quickly decided if the owner would call Mr.Buller in England,He's got the Beesley order book.
These are London proofs,though that is not definitve proof of where it was made.
By the way,where's the whitworth logo on the barells? They're wheat sheaves or somthing like that.
Even if the gun was made in B'ham,if it was sold by Beesley it is well worth the $5500 if not more.