By 1967, the BR wagon fleet had fallen to about a third the size of that inherited in 1948. In an attempt at modernising itself, British Rail launched a programme of vigorous marketing in the 1970s and backed this up with a fleet of new wagons for better bulk handling. The new air-braked vehicles were larger and could travel faster than before and spelt the virtual end of the 10' underframe that had served Britain's railways for so many decades.

For the handling of merchandise we saw the introduction of long wheelbase open wagons and vans with 45 tonnes loading capacity. The open merchandise wagons had an 'O' prefix and 'A' (for air-brakes) suffix and the middle letter denoted the type. The first OBA was built in 1974 and had planked sides. In contrast OCAs, built in the early '80s, were of all steel construction. The OCA was, in fact, a development of the SPA plate wagon and had three drop-down doors on each side. They were the last air-braked open wagons built to a new design, as open vehicles of this type were no longer required for general merchandise by the end of the decade.