The QRB has been designed to release the straps when in unlocked position if it is pressed or struck. For normal operation it is in the closed or locked configeration and is a well tried system. This can be an easy mistake to make if not properly checked or drilled. There are visual checks made to see what "mode" it is in when worn and is a reliable piece of kit when used properly.
Does anyone know what happened on ejection to the Saudi pilot? Did harness totally release from him?
The Koch pins were never fitted to seats in the JP or Victor and were only fitted to a limited number seat types fitted in F4J Phantoms*, some Buccs and early Harriers in RAF service. (*-US surplus).