In the mid-1970s the Nimrod's duties were expanded to include Airborne Early Warning and Control (AEW) — as a replacement for the Lancaster-derived, piston-engined Shackleton which was still in service in that role. The aircraft were modified by British Aerospace at the former Avro plant at Woodford, Greater Manchester to house the GEC Marconi radars in a bulbous nose and tail. From the start of the first flight trials in 1982 the Nimrod AEW3 project was plagued by cost over-runs and problems with the GEC 4080M computer used for the Mission System Avionics (MSA). http://www.spyflight.co.uk/Nim%20aew.htm