The reality is, according to my copy of "Saunders and Saro Aircraft" was that the Princess was built to a specification prepared by the Ministry of Supply, with the assumption (!!) that BOAC would be interested, which they purported to be. Then between the issue of the spec and the commencement of build BOAC seemed to hold diametrically opposed views, depending on who the subject was being discussed with. However in late 1950 BOAC did set up a "Princess Unit", to develop the procedures and infrastructure required. There was some concern at BOAC that the Princess engines were "unsuitable for commercial service", in 1952 BOAC suggested that the (then) new Bristol Orion prop turbine might be suitable, and on it goes.
The end result was that the project was cancelled, and the three airframes (one having flown, the second and third were complete but unflown) were turned into rather a lot of saucepans.
The senior management of BOAC did seem to want to buy US aircraft, rather than British ones. Even when they did "buy British" they complained that the aircraft wasn't suitable for the role. The Vickers VC10 is a classic. BOAC demanded that the aircraft be suitable for "hot and high" airfields typical in Africa. So Vickers built the VC10, sold a handful to BOAC, who then closed the hot and high routes and complained about the high operating cost when competing with 707s on the transatlantic routes.
I find it all very sad.
cheers
Bill