The Avro Type 694 Lincoln is a British four-engined heavy bomber, which first flew on 9 June 1944. Developed from the Avro Lancaster, the first Lincoln variants were initially known as the Lancaster IV and V; these were renamed Lincoln I and II. It was the last piston-engined bomber operated by the Royal Air Force (RAF).
The Lincoln attained operational status in August 1945. It had been initially assigned to units of the Tiger Force, a Commonwealth heavy bomber force which had been intended to play a role in the Japan campaign in the closing stages of the Second World War, but the war ended before the Lincoln could participate. Production of the type proceeded and the type was adopted in quantity, complementing and progressively replacing the Lancaster in RAF service during the late 1940s.
The Lincoln was deployed on operations during the 1950s. RAF squadrons equipped with the type fought against guerrilla fighters during the Mau Mau Uprising in Kenya; the RAF and the Royal Australian Air Force (RAAF) also operated the Lincoln during the Malayan Emergency. The type also saw significant peacetime service with the RAF, RAAF and the Argentine Air Force. Lincolns were also operated in civil aviation, including use as aerial test beds for aero-engine research.