STOKES mortar 81mm
In 1915, Wilfred Stokes designed an 81mm mortar with the idea that British forces could have a weapon which they could face the efective German “Minenwerfers” (mine launchers). Initially the “Stokes 3-in mortar” was rejected by the British Army because it could not use the mortar ammunition available at that time, but finally permission was granted for mass production. The Stokes mortar was a very simple weapon composed by a smoothbore metal tube, a base plate and a bipod. It could fire up to 25 grenades per minute at a maximum distance of about 700 meters, a pretty poor range for a weapon of this caliber, although after the WWI, improvements were made in its ammunition that allowed to achieve a range quite similar to other mortars of the time.
STOKES mortar gallery and more info