Short answers, pulled from the story.
The Directorate of Miscellaneous Weapons Development ordered the Squid weapon directly from a drawing board in 1942. Engineers rushed this new anti-submarine system into active service by May 1943.
A three-barrelled mortar forms the core structure where each projectile weighs approximately 70 pounds and carries a minol II charge inside. Post-war trials later confirmed Squid was nine times more effective than standard depth charges used by the Royal Navy.
HMS Loch Killin achieved the first successful kill using Squid on the 31st of July 1944. Over the course of the war, the system credited with sinking 17 submarines across 50 attacks resulting in a success ratio of 2.9 kills per attack.
Royal Canadian Navy Captain Kenneth Adams strongly opposed fitting Squid to escort vessels because installing this weapon meant sacrificing essential guns from existing ships. Those removed guns would make certain ships unsuitable for major fleet actions against enemy forces.
The Type 61 frigate Salisbury became the last ship to fire Squid in Royal Navy service during April 1977. The Swedish Navy continued using the system until 1982 when their Östergötland-class destroyers were decommissioned.