Part of the reason for the cancellation was the perception that by the time it would enter service, Soviet anti-aircraft capabilities would have improved to the point where it would not be able to succeed in its mission; a preference for missile development over crewed aircraft was another factor.

A successor high-speed bomber flying at low level to evade radar would be developed to meet Air Ministry Specification GOR.339, designated as the BAC TSR-2; however, this too would be eventually cancelled.

During the late 1940s and early 1950s, an entirely new jet-powered bomber fleet comprising three aircraft, the Vickers Valiant, the Avro Vulcan, and Handley Page Victor, which were collectively known as the V-bombers, was developed and introduced to service with the RAF.

[2] Even as the V-bombers were being introduced, the RAF had identified a need for a very-long range supersonic strategic reconnaissance aircraft for the purpose of supporting the V bombers during their offensive mission.

[4] The envisioned reconnaissance aircraft would be capable of successfully entering the airspace of the Soviet Union while avoiding the sophisticated hostile air defences intended to combat such an intrusion.

[5][a] At the time, Britain lacked any operational combat aircraft capable of supersonic flight; as such, meeting the specification required industry to embrace leading edge aerodynamic theory, new materials and futuristic propulsion systems.

[6] As an aid to development, the Bristol Type 188 aircraft was built to test the compound-delta wing shape, and later, the effects of prolonged supersonic flight on metal.

[8][9] The initial version of the aircraft had been intended strictly for the aerial reconnaissance role, for which it would have employed its "Red Drover" sideways-looking radar to find targets for attack by the V bomber force that would follow.

[17] A total of four Armstrong-Siddeley P.156 engines, mounted two apiece in an over-under arrangement of pods positioned at the extreme tips of the wings, provided propulsion.

[18] The aircraft adopted a canard configuration; this approach had the effect of greatly reducing trim-drag, while also generating increased lift at slower speeds.

[17] The Avro 730 lacked a conventional canopy in order to maintain the fineness ratio, the cockpit featured only two small windows facing to the side.

On the intended initial development models, a raised canopy would have been present for direct vision; however, production aircraft would have made sole use of an electrically operated retractable periscope in order to provide an external view, including during take-off and landing.

[4] Fuel onboard had the additional role of serving as a heat sink, and a fully duplicated freon-based refrigeration system provided by Normalair was also present.

[8] Data from Spyplane: The U-2 History Declassified[8]General characteristics Performance Related development Aircraft of comparable role, configuration, and era