Automatic Gun-Laying Turret
The Automatic Gun-Laying Turret (AGLT), also known as the Frazer-Nash FN121, was a radar-directed, rear gun turret fitted to some British bombers from 1944. AGLT incorporated both a low-power tail warning radar and fire-control system, which could detect approaching enemy fighters, aim and automatically trigger machine guns – in total darkness or cloud cover if necessary.
Source: Wikipedia — Automatic Gun-Laying Turret (CC BY-SA 4.0)