Although the initial development contract had been successfully met, BOAC eventually decided to focus on its land-based routes using the jet-powered De Havilland Comet, instead.

Factors such as runway and airport improvements had added to the viability of land-based aircraft, which did not have to compromise to accommodate the additional weight and drag of the boat hulls that were necessary on seaplanes, or the mitigating measures needed against the corrosion caused by seawater.

Following the project's termination, the three airframes were stored with the intention of selling them on, but upon receipt of a promising offer for the aircraft, corrosion was found to have set in while in storage.

[5] While restricted operations of commercial flying boats did continue, such as the use of Boeing 314s for the transatlantic route, many were requisitioned for service with the Royal Air Force (RAF), where they were typically used as maritime patrol aircraft.

[4] During the prewar era, flying boats had been preferred for conducting long-distance flights, as unlike their land-based counterparts, they were not limited by available runway length – the majority of which were still grass-surfaced at this point – and as a long-range aeroplane would be required to carry a large load of fuel, a larger size of the aircraft could be permitted without needing to cater for factors such as limited runway and airfield sizes.

However, the war had also produced a legacy of large runways and sizable airports formerly used for military purposes that could now meet the needs of a larger generation of land aircraft.

The proposed aircraft would be capable of a cruising speed of 340 mph at an altitude of 37,000 feet, a range (dependent on payload) of 5,190–3,640 miles, and be outfitted with luxurious accommodation for a total of 104 passengers.

[8] Following evaluations of a range of different propulsion methods and configurations, the design team selected the undeveloped Bristol Proteus – one of the first turboprop engines – to meet the enormous power requirements of the proposed giant flying boat.

[12][10] Flight tests of the prototype continued until 27 May 1954, by which point the Proteus engine, once perfected, was found to be incapable of enabling the type to achieve its envisioned performance figures.

The company's directors were M D N Wyatt (chairman), Sir Archibald Philip Hope, 17th Baronet, Geoffrey Tyson, P D Irons, and Capt H W C Alger (general manager).

While a decision from the government was pending, the three aircraft were placed into storage, being cocooned and retained, one at Cowes and two at Calshot Spit; work on the programme hopefully would be restarted when a buyer was found.

[18] In 1958, information on the Princess was shared with the United States Navy, which was at the time examining the possibility of converting the three stored aircraft to make use of nuclear power.

[15] In 1964, the three Princesses were all purchased by Eoin Mekie on behalf of Aero Spacelines, which planned to use them as heavy-duty freight aircraft for transporting Saturn V rocket components for NASA.

When the cocooning was removed, they were found to be badly corroded (the contract for maintenance and inspection of the stored aircraft had been allowed to lapse, which resulted in the airframes deteriorating rapidly), and all three Princesses were broken up by 1967.

Conroy considered the creation of an outsize transport from the Princess to have been basically feasible, in that it shares a sectional double-bubble fuselage construction similar to that of the Boeing 377 Stratocruiser, on which the Guppies were based.

Ultimately, this plan was deemed to be impractical, though the existing Guppies continued to function throughout the Apollo program as efficient air transport of the outsize hardware used in these missions.

Designers instead decided to opt for a traditional mechanical-linkage approach that was augmented by a series of electrically driven power-assist units to effectively support actuation.