Roy Chadwick, Avro's chief designer, had foreseen a need for a transport aircraft that was powered by four engines and would be capable of flying for long distances. The design, which was designated as the "Type 685", had its origins in the company's then-newly developed four-engined bomber, the Avro Lancaster, which had made its first flight only earlier that year. The "Type 685" paired various elements of the Lancaster, such as its wings, tail assembly and undercarriage and Rolls-Royce Merlin engines, with a new square-section fuselage that provided double the internal capacity of the Lancaster. The two aircraft also substantially differed in external appearance.