I inherited a couple of old shotguns and I have trouble identifying one of them with precision. It's an old side by side shotgun manufactured in London, with external hammers, damascus barrels and nice engravings still very well preserved. I need some help understanding its value and dating the year of manufacture, if you can.
Doing some research, this is what I found so far:
Gun manufacturer: Dudley Williamson (I found interesting stuff about him, he appeared in court in a murder trial because he sold cartridges to a killer and I found an old advertisement of his business, see attached file)
Country (City): UK (London)
Serial number: #2001
Date of Manufacture: 1906-1920 ?
Proofmarks: Birmingham, should be before 1925
I found only this one on sale:
http://lockyerofengland.co.uk/shop/side ... 1904-1958/ a nice hammerless shotgun by D. Williamson valued 1950 pounds.

I can provide other photos if needed. Thanks and sorry for my English, not my main language