What is the value of Antonio Zoli Silver Falcon over under 12-ga?

I have a silver falcon in Excellent condition non mchoke, i have only been offered £250 part ex, To be honest the gun is worth much more! and is in my opinion equal to a Berreta I shall hang on to this gun.

It has a tapered rib and converging barrels a little on the heavy side but ideal for game or clays and looks good with its sideplates