Welcome Thomas.
I can’t believe WR wants $270 for a gun history letter. On the doublegunshop homepage there is link to “other useful information” and then you can go to “high grade shotguns dates of production”. Based on this link, WR serial number 16000 was made in 1901 and gun serial number 17000 was made in 1908. Your gun was probably made late 1901 or early 1902. The letter from WR will tell you the exact date it was made, quality and features of the gun, and who was the customer. Given the London address it was probably sold out of the London shop and not sold in Birmingham. The proof marks on the barrel flat or they may be on the bottom of the barrels should give a closer date on when the gun went through proof.
Ken
