This interesting little box was sourced from Tocumwal, from a family with an assortment of old Tocumwal Air Base relics. Relics they continued to use in their workshop and work life. Dimensions: 49 x 25 x 26cm.
'Developed by Polish engineers in the late 1930s the Polsten became a cheaper and simpler alternative to the ubiquitous 20mm Oerlikon. The Poles managed to complete a prototype in 1939 just before Germany and the USSR invaded. They smuggled the prototype and designs out of occupied Poland to Britain where Polish, Czech and British engineers at the Royal Small Arms Factory at Enfield completed the development of the weapon.
The Polsten was simpler and easier to manufacture with 119 parts compared to the Oerlikon’s 250. This also meant it was significantly cheaper to produce costing approximately £60 to £70 rather than the £350 it cost to manufacture an Oerlikon. Despite this huge saving the Polsten was a lighter weapon with slightly faster muzzle velocity and a higher effective ceiling with projectiles reaching up to 2,200m (7,200ft).'
Information sourced from:
https://www.historicalfirearms.info/post/151854983984/ordnance-polsten-20mm-cannon-developed-by-polish