 It was a prototype English Electric Type 4, fitted with a design of traction equipment that subsequently appeared later in 1967 as the Class 50, but using a spare bodyshell from the earlier Class 55 'Deltic' Type 5 programme.Locomotive D283, the English Electric type 4 diesel hauling the goods train was undamaged.The wagon derailment was blamed on excessive wear in the suspension components, thought to be caused by cement dust abrasion, in combination with slight variations in both wheel-set diameter and track alignment.