Steamchicken,
The intention was to use the Sea Vixens retired from FAA service as realistic targets to evaluate the effectiveness of various anti aircraft missiles. The drone control pack fitted in place of the observers seat. There were a number of electrical actuators distributed around the aircraft to operate the flight and engine controls, together with an independent system to destroy the aircraft if control was lost when flown as a drone.
To allow the drone control system to be developed, the aircraft could be flown with a safety pilot who could monitor its performance and take over control and land it if the drone system failed. In principle it was a similar system to that recently retired on the USAF F4 Phantoms.
Walbut