The project was eventually cancelled, with the RAF instead purchasing new build Boeing E-3 Sentry aircraft to fulfil the AEW requirement.

[3] Work had been started in the early 1960s on a brand new AEW platform for the Royal Navy to replace the Gannet that would encompass both a new type of radar system mounted on a new aircraft, the P.139.

[5] Around the same time, it was decided not to proceed with FMICW technology as the basis of an AEW system, as research from the United States Air Force (USAF) had shown that pulse-Doppler radar was superior and would be used in the Boeing E-3 Sentry then under development.

A major project management issue was the appointment of British Aerospace (BAe) and GEC Marconi as joint programme leaders.

[8] In 1977 an RAF Comet 4 was modified for flight testing with the nose radome and conducted a series of trials, the results of which proved promising enough for an order for three prototype Nimrods to be built using redundant MR1 airframes.

[9] The first of these was rolled out in March 1980 and flew for the first time in July, and was intended to test the flight characteristics, with the second airframe planned to carry out trials of the Mission Systems Avionics (MSA) package.

[11] The choice of the Nimrod airframe proved to be the wrong one, as it was too small to accommodate the radar, electronics, power generation and cooling systems needed for a system as complex as the one required[12] – at just over 38.5 m (126 ft), the Nimrod was close to 8 m (26 ft) shorter than the Boeing 707 aircraft that formed the basis of the E-3 Sentry, with the planned all-up weight around half that of the American aircraft, but was expected to accommodate sufficient crew and equipment to perform a similar function.

The integration of all of these systems into a single package proved too difficult for the underpowered computer, which had an ultimate data storage capacity of 2.4 MB.

"...The choice of national procurement rather than the available US alternative, involved not only higher costs for Britain but also the lack of an adequate system in-service when needed...

It appears that buying British was given a high priority than having a system available to meet the assessed Soviet threat" At the time that the first production Nimrods were being delivered to the RAF, the MoD decided to conduct a complete review of the AEW programme.

The result of this was the start of a bid process to supply AEW aircraft for the RAF that began in 1986, with a number of different options put forward, including the E-2C Hawkeye, E-3 Sentry, P-3AEW&C Orion, a proposal from Airship Industries, and the Nimrod.

The scandal over the collapse of the Nimrod AEW project was a major factor in Prime Minister Margaret Thatcher's stance to open up the UK defence market to competition.