Input (grade 13): In total, 228 locomotives in the class were built by English Electric between 1957 and 1968, the large number being in part because of the failure of other early designs in the same power range to provide reliable locomotives.
Output (grade 10): 228 locomotives in the class were built by English Electric between 1957 and 1968. The large number was partly to do with the failure of other early designs in the same power range, and reliable locomotives veing needed.