P311 was a Group 3 T-class boat built by Vickers-Armstrong at Barrow-in-Furness and commissioned on 5 March 1942 under the command of Lieutenant R.D.

She was one of only two T-class submarines completed without an Oerlikon 20 mm anti-aircraft gun, the other being HMS Trespasser.

[3] She joined the 10th Submarine Flotilla at Malta in November 1942, and was lost with all hands between 30 December 1942 and 8 January 1943 whilst en route to La Maddalena, Sardinia, where she was to attack two Italian 8-inch gun cruisers, the Gorizia and the Trieste, using chariot manned torpedoes carried on the casing as part of Operation Principal.

Bondone reported that he made the identification based on the wreck having two chariots strapped to her hull.

[4][6][7] The bodies of the 71 crew members and chariot operators who perished are reported still on board, believed to have died of suffocation.