Off topic, I know, but it's interesting to note that of the "classic" British 1960's/1970's jets (VC10, Trident, 1-11) it was only the latter which secured US orders, as did the (later) BAe 146 series, of course.
I would not have thought that range was that much of an issue, but I could be wrong. Standard VC10s were capable of crossing the Atlantic (I flew in one between London and Philadelphia in 1970) let alone Super VC10s. I do recognise that US carriers may have wanted to operate nonstop to places like Rome but I seem to remember that much transAtlantic traffic by Pan Am and TWA was routed via Heathrow. BOAC didn't even serve cities like Detroit nonstop from the UK, presumably partly because traffic on such routes was so thin that it was amalgamated with that to another city. [It's a long time ago and my memory may not have served me well!]
P.S. It has just struck me that BOAC's use of Standard VC10s on the Atlantic might have been forced on the airline as a response to its not being able to introduce the 747 in May, 1970, as planned. The Philadelphia route was, I think, started that year - presumably the idea was to use Supers released by the use of 747s on routes such as LHR-JFK. This must have led to BOAC experiencing a capacity shortage in the summer of 1970. Does anyone know if my speculation is accurate?