I didn't think BOAC went to LA before the days of the 336s and then I didnt think they did non stop . Bangor Maine was favourite tech stop in those days but I do not know if BOAC went there . I had a close friend at the time who was 436 crew and don't recall him going to LA ,
I thought the only LA flight was the Australia the wrong way round VC10 which went LHR-JFK-LAX .
True LA non stop service only began with the shared Air NZ DC10 much later on.