Douglas C-54 and Lockheed C-69 sired civil families from military priority and production volume. All their vendor bits and bobs - the items causing Brit's SNAFUs - emerged from multiple applications, large production runs. Brabazon Type III, to compete with them, was deferred, in the 1943-47 timeframe, because the obvious designers were the Heavy bomber teams, whose efforts were to Pacific schemes (which apart from Avro Lincoln, lapsed), and then to atomic platforms which settled mid-1947 as (to be) V-Bombers.
Bristol had no large structures expertise, but had been selected, 3/43, for Brabazon Type I, in part because they were "spare", in part because their local MP was Minister of Aircraft Production, and in part because their 11/42 bid for a 75ton Pacific bomber included a wing thought fit to lift pax Transatlantic. In 1946 Brabazon III was redefined as Medium Range Empire, selected 7/47, when Avro/HP/Vickers were preoccupied with Bombers, as Centaurus/Bristol T.175: the precise intent was to constrain $ spend by limiting BOAC/BSAAC to a mere few interim US products. So through 1947-50 Bristol tried to do huge Brabazon Type I (T.167) and large MRE, Type 175. Proteus was substituted for Centaurus in 1950; then Korea distracted every vendor. From pressurisation to power, Bristol became overloaded, out-of-their-depth. Piston/MRE had been intended for service by 1950, but entered, as Britannia 102, on 1/2/1957, by when it was a generation adrift in terms of component maintainability/reliability.