WWII Gee navigation system; Wikimedia Commons
Gee was the code name given to a hyperbolic navigation system introduced by the RAF in 1942.
Based on the difference in timing between the reception of two signals, Gee produced a “fix” on a target as far away as 350 miles, with accuracy > several hundred feet.
For night-time bombing of German cities, Gee was accurate enough to be used as an aiming reference without the need of a bombsight. Although German jamming of Gee signals eventually reduced its efficacy, the RAF continued to use Gee as a navigational aid throughout the war.