Thanks again. You did good.
It was made sometime between 1935 and 1939.
Senior New Model - .177 or .22 cal., TL, SP, SS, 416/330 FPS, Bakelite grips, blue finish, adj. rear sight, no safety, 8.5 in overall, 33 oz. Mfg. 1935-1964.
Senior New Model Pre-WWII - plain exterior of barrel ahead of rear sight - a few 1939 guns had knurled barrels, grips w/o Webley name. Judged to be the best of the pre-WWII Webley air pistols.
Over the thirty-year production span of this model, there were at least fourteen variations, different finishes, barrels, etc.
Grading: 95%: $495, 90%: $375, 80%: $300, 70%: $235
Add 30% for original nickel plating.
Add 5% for unmarked rear breech cap.
Add 30% for extra long target barrel.
This info was taken from the latest edition of the Blue Book of Airguns.