Only just caught up with this thread but my best memory of the VC-10 was at Embakasi (Nairobi). I was waiting for a UK visitor on the "waving-base" in the early 70's when an Ethiopian Boeing 720 waddled out for take-off. Bearing in mind that it was mid-day at 5500 feet on the Equator the density altitude was probably around 9000 feet. Off went the 720 emitting filthy black smoke and used just about all of the 3000 metres of runway.(Built courtesy of the Mau Mau but that's another story!). It had just about got enough flying speed to miss Ol Donyo Sapuk about 15 miles away when an East African VC-10 taxiied out and blasted off from the intersection, using way less than half the available. This was exactly what it was designed for so the Vickers engineers got that right but BOAC let them down by not backing it.
Great to fly in too.