The use of spigot mortar anti-submarine weapons had been introduced during the Second World War with the Hedgehog anti-submarine system. In the 1950s this was upgraded to Squid and the final development of the system would be the Mk 10, known as ‘Limbo’. This system was introduced in 1955 and was positioned on the quarter deck of a vessel. It consisted of three launching tubes and was automatically loaded and fired without the crew needing to come out from cover. The mortar fired rounds in a triangular pattern around the ship at a range of 400-1000 yards. The system was used in the Falklands War and remained in service until the 1990s, with an example being preserved at Gosport.
The projectiles themselves had a 12” bore, however they used a smaller launching cartridge and today it is the shell casing from one of these we are taking a look at. Externally it looks just like any other artillery or naval gun casing, being made of heavy grade brass:
The casing has a series of markings on the bottom that indicate it was manufactured in 1959 and is naval in origin (N):
The actual use is indicated by the stamping at the top, which is rather shallow and needs to be in the correct light to be read, but says ‘A.S. Mark 10 Mortar’:
Many of the cartridges used for the Limbo were repurposed from used naval casings, however the lack of crossed out markings on this example suggests it was manufactured for the purpose of being used with a Limbo mortar. Form more details on the cartridges used with Limbo, please look here.