workforce. Its national headquarters were established in Hobart House, London. Formal duties The formal duties of the National Coal Board (defined by Section 1 of the Coal Industry Nationalisation Act 1946) were: History In 1947, about half the collieries were in need of immediate attention and a development programme was begun. Between 1947 and 1956, the NCB spent more than £550 million on major improvements and new sinkings, much of it to mechanise the coal-getting process underground and by 1957 Britain's collieries were producing cheaper coal than anywhere in Europe. The Plan for Coal produced in 1950 aimed at increasing output from 184 million to 250 million tons by 1970. Competition from cheap oil imports arrived in the end of the 1950s, and in 1957 the coal industry began to contract. Between 1958 and 1959, 85 collieries closed. In 1960, Alf Robens became the chairman of the NCB, and he introduced a policy concentrating on the most productive pits. During his ten-year tenure, productivity increased by 70%, but with far fewer pits and a much reduced workforce. In 1967, the NCB reorganised its structure into 17 new areas each employing about 20,000 men. In 1956, 700,000 men produced 207 million tons of coal; by 1971, fewer than 290,000 workers were producing 133 million tons at 292 collieries. The 1974 Plan of Coal produced in the aftermath of the 1972 miners' strike envisaged that the coal industry would replace 40 million tons of obsolete capacity and ageing pits while maintaining its output. By 1983, the NCB would invest £3,000 million on developing new collieries. In 1984, it was alleged that the NCB had a list of collieries earmarked for closure and its chairman, Ian MacGregor indicated that the board was looking to reduce output by 4 million tons, a contributory factor in the 1984–85 miners' strike. The strike was one of the longest and most bitter in history and caused great suffering for the striking miners. During the strike, the NCB lost markets and 23 collieries had closed before the end of 1985. On 5 March 1987, the Coal Industry Act 1987 received royal assent, signalling the end of the NCB and the formation of its successor, the British Coal Corporation. Other activities Railways The NCB operated extensive industrial railway systems at its collieries, employing steam traction until autumn 1982 when Bold Colliery ended regular use of steam locomotives. The NCB's