I serviced seats on Canberras, Hunters and Lightnings. My first encounter with ejection seats was on Canberras. We were tasked with installing the harness release mechanism on the left side of the seat pan and the operating cable to the aircraft floor. This overcame the necessity of the occupant operating the seat harness Now 1000ft straight and level at 70knts. Was a fairly major modification carried out at 2nd line servicing.