Actually, this is an Avro Shackleton AEW.2. It is the ultimate development of the WW.2 Avro Lancaster bomber (through the subsequent Avro Lincoln patrol bomber). It first flew in 1949, and originally served as a long-range patrol aircraft with the British Royal Air Force, but a number were converted into Early Airborne Warning aircraft in 1972 as an interim solution; because the program for its intended replacement (the Nimrod AEW.3) was cancelled, they eventually served until their replacement by the Boeing E-3A Sentry in 1991.