Built by Gloucester C&W, these vehicles are very similar to the Class 116 in construction, but are single units with two cabs. More Class 122s were preserved than Class 121s due to the latter’s extended use in departmental roles, along with the modifications that went with those roles.
Although some were stripped for asbestos removal, five have been preserved in original condition as the class 122s did not have the same refurbishment work as the Class 121s, meaning much more original fittings were present. A further three were later preserved after being released from departmental roles on the mainline, for which they were heavily modified.
They are very popular vehicles on heritage railways, and several now have a bright future with a healthy proportion of the class in operational condition. 55003 was even mainline registered.
More recently, some vehicles have been forcibly removed from traffic as one of the shortcomings of the standard Derby suburban specification (that these vehicles were built to) was a long-term weakness where the roof joins the body. With some vehicles now approaching 20 years in preservation, severe corrosion in this area and around the cabs generally have meant more thorough bodywork has been required to ensure their long term future.