The Handley Page Hereford was a variant on the successful Handley Page Hampden, but powered by Napier Dagger engines. These engines were the downfall of the Hereford. They tended to overheat when used to take off from the grass runways common in the RAF at the time, then cool down too much in the air. Engine failure were too common, and even when the engine worked it was both noisy and high pitched!
The first prototype Hereford flew in June 1937. A production order was placed with Short Brothers and Harland in Belfast, for 100 aircraft, and the first production aircraft flew on 17 May 1939. In all 152 Herefords were built. When the engines worked, performance figures were similar to those for the Hampden, but the engine problems meant that the Hereford never became operational. A small number were used by training units in 1940, but many were converted back to the Hampden standard by swapping the Dagger engines for the more reliable Bristol Pegasus radial engines.