The Hidden report also reacted to criticism of the 1950s-designed Mk 1 coaching stock involved in the accident. The report accepted that withdrawal of the Mark 1 units was not practical and the design was safe: "The inventory of Mark I coaching stock is large, and much of it has not reached an end of economic life, nor will do so for another decade or more. Mark I vehicles have good riding qualities, and are not intrinsically lacking in collision resistance." British Rail was still using multiple units with underframes that had been constructed before World War II and these had priority for replacement.