The business of William Jeffrey was established at,10 Lockyer Street, Plymouth in 1862.In 1865 the business became W.Jeffrey and Son, and relocated to 12 George Street,Plymouth. It remained at this address till 1918 when it moved to 3,Russell Street, Plymouth. It is recorded that in 1933 a Percy Jeffrey rented the shop at 3 Russell street from a F. J. Coles for 100 pounds per year and reopened the William Jeffrey business in its old location.The business continued until 1966 when the name was changed to AR&HV Jeffrey, it is reported that the business closed circa 1982.
Cartridges bearing the W.Jeffrey name,with brand names, The Sky High, Edistone & The Rabbit, were sold from the Russell Street Location.
Your gun is a typical inexpensive Birmingham BLE gun. The proof marks will give some indication as to its date of manufacture.
In proof ,Guns of this quality sell in the U.K. for 800 -1000 U.S. dollars.