The Smith Gun was designed by retired Army Major William H. Smith, a director of an engineering company that produced – amongst other things – toys. The British Army was desperately short of anti-tank guns, having only 167 left in the country after the Dunkirk debacle. This simple smoothbore, man-portable weapon fired modified 3-inch mortar rounds with a theoretical range of up to 500m. In reality the effective range was no more than a fifth of this and the weapon was heartily disliked by its crews in both the Army and the Corps. Evidence exists that it was more dangerous to its operators than those it was intended to be used against. Ultimately it was never used in combat, with just over 4000 being made regular units quickly re-equipped with alternative weapons and it was declared obsolete by 1945.
This gun was an ad-hoc design originating in the days after Dunkirk when the Army needed effective, cheap-to-produce weapons with which to stop a possible German invasion of the UK.