The Class 140 was deemed an overall success, so BR issued an order for an initial production model, designated Class 141, to British Leyland during 1984. During its early years of service, the Class 141 experienced numerous problems, particularly with the transmission and ride quality; work undertaken by BR resulted in the quick development of numerous improvements to at least partially address these shortcomings. When it came to ordering more railbuses, however, it was decided that instead of placing these follow-on orders for further Class 141, it would be more desirable to procure improved derivatives of the Class 141. Accordingly, BR placed orders for two new models of the Pacer family with separate manufacturers, these being the Class 142 and the Class 143.