It fascinates me to look back on our past 'successes' and to see what white elephants they were in real terms when compared with those very few real success stories, where aircraft are produced in greater than 1000-off quantities. One of the key elements is humility, the ability to accept reality and adapt to it. The British national character is one of arrogance and an arrogant political system driving arrogant company management will never yield commercial success.
Several facts of post-war commercial aviation seem to be generally ignored. I wonder why?
1. The WW2 deal was that the USA would concentrate on transports whilst the UK produced combat aircraft. Whatever the final outcome of that war, several consequences were easily foreseeable:
a) that win or lose, the UK would be severely damaged
and lose its empire, and with it its potential transport aircraft export market;
b) that Europe would also be severely damaged, and other European countries' empires would also collapse, and with them, potential European-made transport aircraft export markets;
c) that if the Nazis lost, the European aviation industries would remain fragmented, relying on small domestic markets;
d) that if the Nazis won, then all of Europe would be a domestic market for German transport aircraft, not American
e) but notwithstanding any of the above, a large and expanding domestic US market for US-built transports could be guaranteed.
So a move that appeared entirely sensible and plausible at the time, namely that the UK should concentrate on developing weapons to fight with, was always going to result in the postwar dominance of US transport aircraft.
2. The USA is the only major country not to have had a state-owned National Airline. Evan Pan-Am, the so-called "chosen instrument" of the State Department, was privately owned. Consequently, US airlines have been largely free to pursue purely commercial objectives, and US manufacturers to satisfy those airlines' equipment requirements.
3. The USA is the only Western country that has a domestic aircraft market large enough to sustain the profitable production of 1000+ of a type. The classic postwar US airliners would have sold in profitable numbers
without a single foreign sale.
4. Why do nations have subsidised, state-owned national airlines? In order to carry out their Governments' political wishes. As we can see over and again, those political wishes very often conflicted with "business efficiency" as they resulted in those airlines having to operate unprofitable routes and, often, non-US equipment for political purposes. So it was that the VC-10, specified to operate UK "empire routes" and to operate from short and unimproved runways, was always likely to have higher seat-mile costs than the 707.
If Vickers hadn't had to comply with these requirements, would they have designed the VC-10 as they did? And was there ever going to be a 1000+ market for it in the post-war Marshall Plan world, in which the USA was making quite sure that Britain took its post-imperial "rightful place" in the global power structure? The USA's entry into WW2 was its bid for global domination. The Marshall Plan was the outcome. The USA always plays to win.
5. All of the successful postwar non-US types have been commercially successful because they were the first in their fields with no US-made equivalent and offered very significant performance improvements, operating cost reduction and passenger appeal when compared to existing US types: the Viscount, the Caravelle, the BAC 1-11. All achieved US sales. Even the Britannia did. The Comet and Concorde might well have joined this roster had events not turned against them. No other post-war non-US type ever stood a chance, commercially.
Edit: I should add the Fokker F27 to this list of successful non-US types, of course. As the first pressurised turboprop "DC-3 replacement" it was commercially successful for the same reasons that the others in this list were.
So were they white elephants? No. They carried out a strategic political function in maintaining the non-US aviation industrial base that gave rise to Airbus, a multinational consortium that eventually could command a potential non-US market to the extent that it could achieve 1000+ sales
without needing sales to the USA, and thereby finally matching the potential of the US domestic market.
And, famously, passengers much preferred the Iron Duck to the 707. BOAC flew it more profitably on the North Atlantic than the 707.
Edit: The Iron Duck is, of course, the Vickers VC-10.