At the time, the Saunders-Roe Princess was one of the largest aircraft in existence; unfortunately, by the 1950s, the concept of a flying boat was dead. Better runways and airports meant that future long-range airliners would be land-based aircraft, without the weight and drag of a boat hull.
The Princess was powered by ten Bristol Proteus turboprop engines, powering six propellers. The four inner propellers were double, contrarotating propellers driven by a twin version of the Proteus, the Bristol Coupled Proteus; each engine drove one of the propellers. The two outer propellers were single and powered by single engines.
The rounded, bulbous, 'double-bubble' fuselage contained two passenger decks, with room for 105 passengers in great comfort.
The prototype, G-ALUN, first flew on August 22, 1952. It was the only one to fly. Two others (G-ALUO & G-ALUP) were built, but they never flew. After spending a number of years in mothballs awaiting possible future use, all were broken up in the 1960s.
They were the last fixed-wing commercial aircraft produced by Saunders-Roe. The company built one more fixed-wing design, the Saunders-Roe SR.53 rocket-assisted experimental fighter; aside from that, the company concentrated on helicopters and hovercraft after this point.