In June 1941 the Birmingham Carriage and Wagon Company was given the job to develop a self propelled gun that could carry the 25 pdr howitzer. This was to allow the 25 pdr artillery batteries to quit having to fight as antitank weapons and just concentrate as being artillery. However, by the time the Bishop came to the field the 25 pdrs were no longer being used as antitank guns and the Bishop was then relegated to being an artillery self propelled gun.
The Valentine Mk II chassis was used. Its turret was replaced by a large box that mounted the 25 pdr gun.
The Bishop's main armament couldn't be elevated to its maximum level so it was relegated to a close support role or ramps had to be built to drive the Bishop onto. There were two large doors that were typically left open when firing to allow the crew extra room.
The 25 pdr's range was about 6,400 yards.