Early on, it was recognised that the Class 150 would be unsatisfactory in some criteria for more-upmarket services, but that a derivative of the type would likely better handle these services. Thus, such DMUs were built by British Leyland at Workington (using a body construction technology derived from the Leyland National bus) between 1987 and 1988.
Initially, it was determined that the Class 150 would not meet all requirements for premium services, but a modified version of the design would be more suitable. As a result, DMUs were constructed by British Leyland at Workington (using body construction techniques derived from the Leyland National bus) between 1987 and 1988.