The Avro Type 679 Manchester was designed by A V Roe & Company (Avro) Chief Designer Roy Chadwick to Specification P.13/36 which called for a twin-engined medium bomber. Two prototypes were ordered (L7246 and L7247), the first of these flying for the first time at Manchester Ringway on 25th July 1939. Avro selected the 1,760 hp 24-cylinder Rolls-Royce Vulture I engine to power the Manchester.
When initially flown, the Manchester tail section featured a low-set tailplane with twin fins. Following early test flying, a third central fin was fitted although only the outer fins were fitted with rudders.
The second prototype (L7247) flew in May 1940, and was fitted with defensive armament comprising front, rear and ventral Frazer Nash turrets, each fitted with two 0.303 machine guns. The wingspan of the second prototype was increased by nearly ten feet in comparison to the first aircraft.
An initial production order for 200 Manchester I aircraft was placed against Specification 19/37, these aircraft differing from the second prototype in having the ventral turret replaced by a more streamlined dorsal turret. A further 100 aircraft were ordered from Metropolitan-Vickers Ltd, to be built at Trafford Park.
Deliveries from A V Roe commenced in July 1940, with Metropolitan-Vickers aircraft following a full nine months later. These had been severely delayed when their Trafford Park factory was extensively damaged by a bombing raid in December 1940. This resulted in the total destruction of what would have been their initial batch of thirteen Metropolitan-Vickers aircraft and delayed the first aircraft delivery until March 1941.
Manchester production was curtailed due mainly to the type's poor reliability on operations, but the promise of a much superior performance from a four-engined, Rolls-Royce Merlin-powered, Avro 698 Lancaster also played a large part in the decision. The four-engined development, using Merlin engines, was trialled by modifying a Manchester (BT308), which effectively became the first prototype Avro 698 Lancaster.
The first RAF unit to operate the Manchester was 207 Sqn with its first operational sortie on 24/25th February 1941. The Vulture engines suffered frequent failures but by then Rolls-Royce had directed all of its attention to progressive development of the Merlin engine, rather than diverting resources to its troublesome forerunner.
Later production aircraft can be recognised by a modified empennage and by the tailplane span being increased to 33 feet. The outer tailfins were also increased in height and made more elliptical in shape whilst most obvious of all was that the central fin was removed. Additionally, a four-gun rear turret was also adopted on this version and in this form, the type was redesignated as the Avro 679 Manchester Mk IA and all Manchester Mk I aircraft were progressively modified to Mk IA standard.
The Manchester was withdrawn from operations in mid-1942, following which it was used as a trainer to convert crews to the Lancaster, and was retired from service in 1943.
The final production numbers were two prototypes plus 157 production aircraft built by Avro and 43 by Metropolitan-Vickers, making a total of 202.