Thanks for the info Ironsides0 but we in engineering heard that BEAs precurment department insisted that the original Trident which was nearly the same size as the B727 was too big and insisted it was downsized to what became the Trident 1 with an engine that was not suited to it as it was "off shelf"ie the Spey instead of a new engine Rolls was going build for it, it was not called the "Ground Gripper" for nothing by the time we got to the Trident 3 it was nearer to the b727 but was lumbered with a 4th engine and all that entailed and of course the 727 was a cheaper proposition by then . the only redeaming feature was the Trident was more technicly advanced in the Auto pilot dept and was the for runner of the Cat 3 landings and Automatic landings which non of the early Boeings had ,Im ready to be shot down in flames by saying the first commercial Boeing to have Autoland was the B747/400 and that was because Lockheed brought out the L1011 Tristar with it built in.