mmppres,
Nice little piece, often seen in nickel coated, but you have a great little Webley Pocket WP Hammerless 6 round pistol there in what looks good used clean condition.
You'll need 7mm (.320) rounds. Stopped production long before WW2, but were often found in NI on weapons searches or finds.
I think you'll find it a beauty to shoot to. Real shame we haven't seen them in the UKicon mainland for years.