SAS -the British aviation industry did not go away; it consolidated and downsized and was nationalised for a period, but it is still ranked as the 2nd or 3rd largest in the world, dependent upon the way the figures are interpreted.
Dunc - in 1965, the conditions which the US wished to seek to impose for support for an additional loan from the IMF were based around the desire to see the UK staying east of Suez, and (LBJ hoped) sending troops to Vietnam. There were much bigger fish to fry than cancelling 20 Belfasts for C-130s - which, in any event, were the replacement for the HS681 rather than additional Belfasts. If any skulduggery occurred, it'd have been the HS681 that got it in the neck.
[1] And with respect, while the US has often pursued its interests in a manner which upsets the Daily Mail and which gives the lie to ideas of extra-special friendship/treatment
The question you ask about the Belfast is covered in some detail
here
[1] - And the alleged skulduggery is probably along the lines of that seen with TSR2: non-existent. In that case, the US attitude was one of 'They're cancelling [/I] it? Seriously?, and concern over the implications of having the Canberra 8 in service in Europe in the 1970s was in no small part responsible for the US falling over to offer good terms for the F-111. Remember also that the Labour government had a very jaundiced view of the British aircraft industry - Healey used the phrase "wet nursing mentally retarded children" - see here, although note his claims as to what he was referring to - while concern over project management and rising defence costs was growing; buying OTS in the form of Phantom and Hercules was not exactly the most stupid idea that Wilson's administration ever had.