In 1967 all three works became part of the nationalised British Steel Corporation (BSC), leading to a period of further consolidation – from the 1970s the use of local or regional ironstone diminished, being replaced by imported ore via the Immingham Bulk Terminal. Conversion to the Linz-Donawitz process (or "basic oxygen" process) of steel making from the open hearth process took place from the late 1960s onwards and was complete by the 1990s. Both the Normanby Park and the Redbourn works closed in the early 1980s.