Thanks for the excellent link Tu114, but being in BOAC at the time, my memory tells a slightly different story.
Whilst the Standard VC10 was intended for the hot climates, the Super specification from BA
was that it should have a longer range than the 707, as mentioned above, and emphasised the ability to fly from UK to the West Coast of US.
When it was found that this range was not achievable, BA
cancelled the additional Supers. BAC in retaliation reduced the number of spares needed for support downroute, so for a while the Super operated only LHRNYCLHR.
The 707s were not brought in to replace the VC10, they were there already with Rolls Royce 436s operating from around 1958 - the Comet, of course, was the first trans-atlantic jet, just beating the 707 to the post!
I worked on these 707s in the early 60s, and from late 1962, we did operate into Kano, Lagos, Karachi, Singapore, as well as Teheran, Delhi, Rangoon, Bangkok, and Hong Kong, with no trouble at all!
Later, a few more 707s BOAC were delivered, the first two from Cunard Eagle, which then merged into BOAC Cunard. Later again, some P&W engined versions arrived. These had not been allowed on the initial BA
order, as the British Government at the time decided that all BOAC's 707s must have RR
Anyway, my two pence . . . !
Per Ardua ad Astra! ........ Honi Soit Qui Mal y Pense!