Coal mines had vast fleets of coal wagons which were usually of the 7-plank design and many a local coal merchant had one or two to bring his stock of coal for bagging up in the local station yard. Between these two there were coal factors who traded in coal on a large scale, supplying industry, ports and domestic needs with their own privately owned, or leased, fleet. Whether owned by the mines, factors or local coal merchants, 7-plank wagons all carried the livery of their owner or operator and, as such, added greatly to the colourfulness of the railways.

At one time the 7-plank wagon was the most numerous type of wagon on Britain's rail network and almost all were involved in the coal business. Indeed, 75% of all privately owned wagons were operated by colliery companies. They were privately owned up until the Second World War, when they were pooled for the war effort and, with the nationalisation of the mines and the iron and steel industry in 1947 and railways in 1948, they became state owned.

A considerable number of them were acquired by the National Coal Board for internal use. Those that passed to British Railways were repainted in grey and given a new fleet number with a 'P' prefix. After years of neglect due to the privations of war they were largely ‘past their sell-by date’. An intense cull took place in the 1950s as they were replaced by 16 ton all-steel mineral wagons so that, by the end of the decade, few remained on the railways.