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 .
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 .