In 1964 Hawker Siddeley began development of a maritime reconnaissance aircraft to replace the ageing, piston-engined Shackleton in service with RAF Coastal Command. Its HS.801 design used the airframe of the de Havilland Comet as a basis, but incorporated a ventral weapons pannier to give a new double bubble cross section and powerplant of four Spey turbofans. The prototype made its maiden flight on 23 May 1967 and the first of 46 production Nimrod MR.Mk 1s flew on 28 June 1968. The type entered service in 1969. Eleven MR.Mk 1s were later converted in the early 1980s to Nimrod AEW.Mk 3 standard in an abortive programme to provide the RAF with a new airborne early warning aircraft.
The Nimrod is capable of conducting surveillance over land and sea, submarine attack and perform search and rescue missions.
From 1975 MR.Mk 1s were upgraded to MR.Mk 2 standard, the first such conversation being redelivered to the RAF in August 1979. This variant introduced a completely new avionics and equipment suite, including a GEC central tactical system, a Thorn EMI Searchwater radar and an acoustics system compatible with modern sonobuoys.
The addition of an inflight-refuelling probe for the 1982 Falklands war created the Nimrod MR.Mk 2P - the P was subsequently dropped in the late 1990s. Wingtip-mounted Loral ESM pods were added later. Several Nimrods detached to Oman for Operation Desert Storm were modified with an underwing forward-looking infra-red, BOZ electronic counter measures pod and a towed radar decoy.
During the mid-1990s, BAe was selected to update 21 Nimrods to MRA.Mk 4 standard. This involved a virtual total rebuild of the airframe, installation of 66.73-kN BMW Rolls-Royce BR.710 turbofans, strengthened undercarriage and new avionics and sensor suites that will maintain the Nimrod's capabilities at a very high standard. The programme is scheduled to deliver these revitalized machines in 2010.
Three further aircraft designated Nimrod R.Mk 1 serve in the electronic intelligence-gathering role. A crashed R.Mk 1 was replaced by converting a spare MR.Mk 2 airframe in 1997.
The Nimrod Mk.2 was finally withdrawn from service in 2010 and is due to be replaced with the Nimrod Mk.4.
During over 30 years of service Nimrod force performed a wide variety of roles in support of UK's defense. It has been involved in every major conflict in the last 30 years.