British Railways had around a quarter of a million steel mineral wagons. These took over the work of the ageing PO 7-plank wagons, dominating coal, stone and iron ore transportation in the '50s and '60s. The standard design was the ubiquitous 16 ton all-steel end door mineral wagon, built for British Railways in their tens of thousands throughout the 1950s. Before the war, 14 and 15 ton all-steel mineral wagons had been built by Charles Roberts and the Butterly Company as replacements for wooden coal wagons. Some were bought by private owners but, along with the rest, they were requisitioned by the government on the outbreak of war. The Ministry of Transport (MoT) started ordering 16T steel wagons for use in France and for replacements at home. They had a 9' wheelbase and those built by Charles Roberts & Co. had sloping sides. The building of the 16T all-steel mineral wagons carried on unabated throughout the 1950s but finished in 1959.