Tridents and speed
I remember two occasions where the flight deck cheerfully pointed out how fast the trident could go . Once going to Stockholm we overtook a Scandi DC9 which the captain said had left LHR 15 mins in front of us and we caught up by the Danish coast, I guess he knew the call sign/flt number as about every other aircraft around there would have bena Scandi DC9 .
Othertime was Rome to LHR and we overtook a VC10 en route , this seemed to give the crew particular pleasure to be going faster than 'the other lot''
As to the Gripper nickname having seen innumerable take offs from what was 28L the Trident didnt look too bad. It couldnt match the DC9s , the Comet4Bs it was replacing, or the occasional 707s (only going as far as Brussels or Paris ) or even Caravelles. but of course, 2 engined airliners are all somewhat overpowered since they need to survive with one if there s a problem and back then i dont think there was much reduced thrust take off going on. I think the Trident was going pretty fast at unstick speed compared to some bigger-winged/more modern types so perhaps that made it look more scary.
As to the boost engine , that amde a distinctive noise and was clealry different from the 1s and 2s. I think it was more widely used than has been suggested I often saw/heard them use in departing 10R which even if they left from one of the intersections (block79) it was still a pretty long runway. Tridents used to emit wisps of white smoke/steam as they started rolling any ideas what that was about. of course it was nothign to the clouds of muck from CV990s, 727s and even Electras