The Manchester has its origins in a design produced by Avro in order to fulfil the British Air Ministry's Specification P.13/36. This was the same specification to which Handley Page had also produced their initial design for what would become the Halifax bomber. Issued in May 1936, Specification P.13/36 called for a twin-engine monoplane "medium bomber" for "worldwide use", which was to be capable of carrying out shallow (30°) dive bombing attacks and carry heavy bombloads (8,000 lb/3,630 kg) or two 18 in (457 mm) torpedoes. Additionally, it had to feature provisions to conduct catapult assisted takeoffs, which would permit the carriage of the maximum payload, was also a stated requirement, although this provision was explicitly removed in July 1938. The envisioned cruising speed of the bomber was to be a minimum of 275 mph at 15,000 feet. The Air Ministry had expectations for an aircraft of similar weight to the B.1/35 specification, but smaller and faster.