Originally conceived by Hunting Aircraft as a 30-seat jet, before its merger into BAC in 1960, it was launched as an 80-seat airliner with a British United Airways (BUA) order on 9 May 1961.

The short haul, narrowbody aircraft was powered by aft-mounted Rolls-Royce Spey low-bypass turbofans, a configuration similar to the earlier Sud Aviation Caravelle and later Douglas DC-9.

In the 1950s, although the pioneering de Havilland Comet had suffered disasters in service, strong passenger demand had been demonstrated for jet propulsion.

[3] In July 1956, British European Airways published a paper calling for a "second generation" jet airliner to operate beside their existing turboprop designs.

[8] Market research showed the 59-seat BAC 107 was too small, and the design was reworked in 1961, with passenger capacity growing to 80 seats, and BS75s being discarded in favour of Rolls-Royce Speys.

[12] Mohawk Airlines sent representatives to Europe seeking out a new aircraft to bring them into the jet era, and on 24 July 1962 concluded an agreement for four One-Elevens.

The prototype (G-ASHG) rolled out of Hurn assembly hall on 28 July 1963, at which point BAC had received orders for the type from a number of operators.

The first flight had taken place almost a year before the Douglas DC-9, a rival American jetliner; BAC considered the One-Eleven to hold a technological edge.

This gave competing US aircraft (the Douglas DC-9 and Boeing 737) the opportunity to compensate for the One-Eleven's early penetration of the US domestic market.

The type saw service with Cayman Airways and Leeward Islands Air Transport (LIAT) in the Caribbean with Cayman Airways operating the series 500 on scheduled services to Houston, Texas (IAH) and Miami, Florida (MIA), and LIAT flying its series 500s into San Juan, Puerto Rico (SJU).

It combined the 400 fuselage with the higher power and larger wing of the 500 and was intended for hot and high as well as rough airfield operations; however only ten One-Eleven Mk 475s were sold with one airline being Faucett Peru which operated its series 475 aircraft on scheduled domestic services into several airports with unpaved gravel runways in Peru.

[25] There were two reasons why the production line was kept open for just 35 aircraft delivered over 11 years: first, BAC hoped that Rolls-Royce would develop a quieter and more powerful version of the Spey engine, making possible further One-Eleven developments; second, throughout the early part of the period Romania was negotiating to buy the entire One-Eleven programme and transfer production of the type to Bucharest.

[28][29] The 700J was planned for the Japanese market, with the same stretched fuselage and engines as the 700 and a new high-lift wing for operation into regional airports with short runways.

[31] In 1977, BAC merged with Hawker Siddeley to form British Aerospace (BAe) and the new company was faced with the choice of developing the X-Eleven or joining European efforts to design an-all new aircraft.

This was to involve the delivery of three complete One-Elevens (two 500-series aircraft and one 475 series) plus the construction of at least 22 in Bucharest, with the reduction of British (and thus increase of Romanian) content.

It also involved Romanian production of Rolls-Royce Spey engines and certification of the aircraft to British standards by the Civil Aviation Authority.

A market for up to 80 Romanian-built aircraft was projected at the time, largely in China and other developing economies, and possibly Eastern Europe.

Romania's economy and international position deteriorated to the point where supplies needed for One-Eleven manufacturing slowed to a trickle, with hard currency restrictions delaying the delivery of components sourced outside Romania;[33][36] the market foreseen by the Romanians failed to show an interest, though some Rombac machines were leased to European operators.

Despite this setback, Rombac continued to try to sell the One-Eleven, with US operator Kiwi International Air Lines placing a firm order for 11 Tay-engined aircraft with options for an additional five, but these plans never happened.

[40] In the US, the Civil Aeronautics Board was sceptical of smaller operators' need for jet aircraft and withheld financing, leading to several US customers cancelling their One-Eleven orders.

[43] Buying the jets pushed Mohawk into debt and this, along with an economic downturn and strike action, led to its forced merger with Allegheny Airlines which in turn continued to operate the One-Eleven.

Passenger demand grew on several key One-Eleven routes, exceeding the Series 500's larger capacity during the 1980s, which began to force airlines to use other planes.

British Airways Regional Division found the performance of the One-Eleven more than adequate and sought to expand operations with the type, including further acquisitions, in the early 1970s in part to replace Vickers Viscounts.

BA proceeded to rationalise its fleets, retiring many overlapping types, the One-Eleven being gradually phased out for the more modern A320 and Boeing 737 jetliners.

In another high-profile incident on 21 May 1982, John Clearno tried to hijack a Philippine One-Eleven while on the ground, but was eventually overpowered by the cockpit crew following hours of negotiation.

In May 1977, a major cooperation agreement between British Aerospace and the Romanian government was signed, and this led to a gradual One-Eleven technology transfer to Romania.

Rombac-produced One-Elevens would be adopted by many emerging operators globally, including Lauda Air in Austria, and Aero Asia International in Pakistan.

A major factor for the withdrawal from European service of remaining One-Elevens was the Stage III noise abatement regulations, which came into effect from March 2003.

Bringing the Rolls-Royce Spey engines into compliance with the noise regulations with hush kits was expensive, and many European operators chose to dispose of the type from their fleets.

As a result, BAC One-Eleven aircraft registered in any EU Member State are no longer eligible for a normal certificate of airworthiness.