[5] A great deal of interest in the requirement was received from both British and foreign manufacturers, who offered aircraft including the Lockheed P-3 Orion, the Breguet Atlantic and derivatives of the Hawker Siddeley Trident, BAC One-Eleven, Vickers VC10 and de Havilland Comet.

[6][7] On 2 February 1965, Prime Minister Harold Wilson announced the intention to order Hawker Siddeley's maritime patrol version of the Comet, the HS.801 as a replacement for Shackleton Mk 2.

The Comet's turbojet engines were replaced by Rolls-Royce Spey turbofans for better fuel efficiency, particularly at the low altitudes required for maritime patrol.

Major fuselage changes were made, including an internal weapons bay, an extended nose for radar, a new tail with electronic warfare (ESM) sensors mounted in a bulky fairing, and a MAD (magnetic anomaly detector) boom.

One R1 was lost in a flying accident since the type's introduction; this occurred in May 1995 during a flight test after major servicing, at RAF Kinloss.

The last flight of the type was on 28 June 2011 from RAF Waddington, in the presence of the Chief of the Air Staff, ACM Sir Stephen Dalton.

Changes included the replacement of the 1950s ASV Mk 21 radar used by the Shackleton and Nimrod MR1 with the new EMI Searchwater radar,[N 2] a new acoustic processor (GEC-Marconi AQS-901) capable of handling more modern sonobuoys, a new mission data recorder (Hanbush) and a new Electronic Support Measures (Yellow Gate) which included new pods on the wingtips.

[19][21] Provision for in-flight refuelling was introduced during the Falklands War (as the MR2P), as well as hardpoints to allow the Nimrod to carry the AIM-9 Sidewinder missile to counter enemy Argentine Air Force maritime surveillance aircraft.

Its extended range enabled the crew to monitor maritime areas far to the north of Iceland and up to 2,200 nautical miles (4,000 km) out into the Western Atlantic.

Eleven existing Nimrod airframes were to be converted by British Aerospace to house the GEC Marconi radars in a bulbous nose and tail.

[27] Eventually, the MoD recognised that the cost of developing the radar system to achieve the required level of performance was prohibitive and the probability of success very uncertain, and in December 1986 the project was cancelled.

The type had been originally intended to enter service in 2003 but was cancelled in 2010 as a result of the Strategic Defence and Security Review, at which point it was £789 million over-budget;[3] the development airframes were also scrapped.

[10][33] Aircraft in this role had been commonly propelled by piston or turboprop powerplants instead to maximise fuel economy and enable maximum patrol time on station.

[37] Electrical generation was designed to far exceed the consumption of existing equipment to accommodate additional systems installed over the Nimrod's service life.

In the event of war, reconnaissance information gathered during these patrols would be shared with other allied aircraft to enable coordinated strikes at both submarines and surface targets.

[35] A significant proportion of the onboard sensor equipment was housed outside the pressure shell inside the Nimrod's distinctive pannier lower fuselage.

[11] To support the Nimrod's anticipated long lifespan, onboard computers were designed to be capable of integrating with various new components, systems, and sensors that could be added in future upgrades.

[40] The Nimrod featured a sizeable bomb bay in which, in addition to armaments such as torpedoes and missiles, could be housed a wide variety of specialist equipment for many purposes, such as up to 150 sonobuoys for ASW purposes or multiple air-deployed dinghies and droppable survival packs such as Lindholme Gear for SAR missions; additional fuel tanks and cargo could also be carried in the bomb bay during ferrying flights.

[43] Various new ECMs and electronic support systems were retrofitted onto the Nimrod fleet in response to new challenges and to increase the type's defensive capabilities; additional equipment also provided more effective means of identification and communication.

[49] The safeguarding of the Royal Navy's Resolution-class ballistic missile submarines, which were the launch platform for Britain's nuclear deterrent, was viewed as being of the utmost priority.

[50] Nimrods were first deployed to Wideawake airfield on Ascension Island on 5 April 1982,[51] the type at first being used to fly local patrols around Ascension to guard against potential Argentine attacks, and to escort the British Task Force as it sailed south towards the Falklands, with Nimrods also being used to provide search and rescue as well as communications relay support of the Operation Black Buck bombing raids by Avro Vulcans.

[53] Aviation author Chris Chant has claimed that the Nimrod R1 also conducted electronic intelligence missions operating from Punta Arenas in neutral Chile.

[54] The Chilean government allowed an RAF Nimrod R1 to fly signals reconnaissance sorties from the Desventuradas Islands, gathering information on Argentine Air Force movements.

Due to the level of threats present in the Gulf theatre, operational Nimrods were quickly retrofitted with a Marconi towed active decoy.

[23] After the ground offensive against Iraqi forces had ended, Britain elected to maintain an RAF presence in the region through assets such as the Nimrod and other aircraft.

The main role would normally be to act as on-scene rescue coordinator to control ships, fixed-wing aircraft, and helicopters in the search area.

[46] In August 1979, several Nimrods were involved in locating yachting competitors during the disaster-stricken 1979 Fastnet race and coordinated with helicopters in searches for survivors from lost vessels.

During the Icelandic Cod Wars of 1972 and 1975–1976, the Nimrod fleet closely cooperated with Royal Navy surface vessels to protect British civilian fishing ships.