This information may or may not be of interest re Leeches of Rochester .An anti submarine bomb named Squid , was the main underwater warfare weapon of the RN.at that time. Bomb shaped it was fired from a 'mortar ' ahead of the ship. It was fitted with a depth detonation setting device,covered by a lens to facilitate setting (very small numbers ,hard to see) the lenses were all manufactured at Leeches ,of Rochester . We had boxes of them on hold in Lodge Hill RNAD.