The Shackleton was designed by Roy Chadwick as the Avro Type 696. It was based on the Lincoln bomber and Tudor airliner, both derivatives of the successful wartime Lancaster heavy bomber, one of Chadwick's earlier designs which was the then current ASW aircraft. The design took the Lincoln's center wing and tail, Tudor outer wings and landing gear and a new wider and deeper fuselage, powered by four Rolls Royce Merlin engines. It was initially referred to during development as the Lincoln ASR.3.