I seem to remember BOAC had alternating VC10 and 707 flights. In the latter half of 1967, everyone was getting excited about the prospect of a VC10, most of us having arrived there in the first place on Britannias. In my case, that was a British Eagle Brit, G-ANCF (Ironically, post British Eagle, this aircraft went to Monarch!) When my turn to go home in October 1967 came, 6 of us were allocated seats on .... Yep! A Britannia! This time it was the ill fated XL638, fitted out primarily as a cas evac plane with arrangements for lots of stretchers and a wide door which allowed the ambulances to reverse up a ramp to the aircraft. (Hence the only 6 "regular" passengers). And, while the lucky sods going home on one of these new-fangled jets were there within a few hours, we had to endure 20 hours from Aden to Lyneham!