A little addition on the 707-436 timeline ,I flew on one on my honeymoon (why I remember it so clearly) to Faro from LHR in late March 77. I think though it may have been borrowed from Airtours due to having HF radio and needing to avoid French ATC or something similar.
Also took an interest as had a friend who was 436 pilot though he may he been on temporary lay off at that time too.
For all thats been said about them at airshows I also remember it for being stunningly noisy inside with those 4 Conways crackling and roaring away . Came back on a Trident 3 which was much nicer to fly on
PB