With the closure due to complete workout in 1927 of the Craven Colliery, all miners were transferred to the Coventry Colliery. With significant contracts to supply coal to electricity generation stations in Birmingham and Coventry, including the Hams Hall power stations, the company hired in over 1,000 coal wagons. By 1939, the last year of full production before the Second World War, the colliery was producing over of coal per annum. Nationalised on 1 January 1947, the colliery became part of the National Coal Board's (NCB) Area 4 (Warwickshire). In the early 1960s, the NCB started a development of a smokeless coal plant, known as a Homefire Plant, on site. This came into production in 1967, and resultantly in an NCB reorganisation the Coventry Colliery became part of the South Midlands Area (SMD). The colliery closed for redevelopment in October 1991, with the site handed over to the local authority in 1996. The Homefire Plant closed in 2000. Originally, the colliery had its own branch from the Coventry Canal. But the large amounts of spoil created, and the reduction in shipping charges associated with building materials, necessitated the building of a temporary private railway, which connected with the LNWR's Coventry to Nuneaton Line at Three Spires Junction near Foleshill. In 1919, with the return of the men from the First World War, production increased. The line was hence rebuilt as double track with extensive sidings adjacent to Three Spires Junction, and formally used for the distribution of extracted coal. On site the railway operated both and , the later used for the distribution of spoil and goods onsite. The company bought its own locomotives to operate these private lines, bought new and secondhand from a range of manufacturers, including Andrew Barclay Sons & Co., North British Locomotive and Peckett and Sons. In the early 1960s, with the Beeching Axe making ex-British Railways (BR) steam engine types cheaply available, the NCB bought three ex-Great Western Railway 1500 Class 0-6-0 Pannier Tanks in 1962, No.s 1501, 1502 and 1509. All three were sent to Andrew Barclay Sons & Co. in Scotland for refurbishment before use on the colliery system, and their being brought into operation resulted in all of the other existing standard gauge locomotives being scrapped onsite. In 1970, the NCB contracted in British Rail Class 08 diesel shunters.