Early development and John Calvert The colliery was established in August 1851 by
John Calvert, a
Yorkshire railway contractor who had previously worked as the major contractor for
Isambard Kingdom Brunel’s
Taff Vale Railway construction in the 1840s. After initially being distrustful of Wales, Calvert remained in the area following completion of the railway in 1841 and switched his focus to mining operations. Calvert had established his mining credentials with the successful
Newbridge Colliery at Gelliwion,
Pontypridd, which he sunk in 1844 to work the No.3 Rhondda seam at 55 yards depth.
Great Western Railway involvement However, after only three years of operation, Calvert found himself in financial difficulties and decided to sell the colliery and its coke oven plant to its major customer, the Great Western Railway Company, who bought the colliery after a three-month trial period in 1854. The Great Western Railway operated the colliery directly from 1854 until 1864 at great profit, during which time they developed the site extensively and sank additional shafts. However, the railway company advertised the colliery for sale on 19 March 1864, as part of a broader rationalisation of their non-railway assets.
Great Western Colliery Company formation The sale process proved complex, with considerable delays before the colliery was finally transferred to new ownership on 1 April 1865. Financial difficulties led the Great Western Colliery Co. Ltd. into voluntary liquidation on 18 March 1878 "for reconstruction purposes". A new company of the same name was registered on 1 November 1878 to continue operations, demonstrating the ongoing commercial viability of the mining operation despite the corporate restructuring. The disaster occurred during the day shift when 950 of the colliery's approximately 1,460 workers were underground. Contemporary reports indicate that by 14 April, 53 bodies had been recovered from the affected workings. The fire originated at a haulage engine located in the East Hard Heading, about 120 yards from the Hetty Pit, where compressed air was used to power underground machinery from surface compressing equipment. The colliery employed sophisticated ventilation systems including two Schiele fans, each of fifteen feet three inches diameter, positioned at the pit tops to maintain air circulation throughout the extensive underground workings. Powell Duffryn had expanded rapidly during the 1920s through acquisition of major Welsh mining operations, including the Rhymney Iron Company,
Windsor Colliery, collieries from Lewis Merthyr, and the Great Western Colliery Company. Under Powell Duffryn's management, the Great Western Colliery was incorporated into a larger strategic operation. By 1934, the Great Western Colliery Company (as a subsidiary of Powell Duffryn) controlled three collieries employing 2,270 men who produced 650,000 tons of coal annually. The company directors at this time included E.L. Hann, W.R. Hann, Sir Francis Kennedy McLean and Evan Williams. This period saw significant modernisation efforts. The colliery benefited from Powell Duffryn's policy of concentrating investment in their most productive operations, with new shaft developments and improved surface facilities enhancing operational efficiency.
Nationalisation and final operations The Great Western Colliery, along with the entire
British coal industry, was nationalised on 1 January 1947 under the
Coal Industry Nationalisation Act 1946, becoming part of the
National Coal Board's South-Western Division. The NCB took control of 958 collieries across Britain, with the South Wales operations forming a crucial part of the nationalised industry. A major reorganisation occurred in 1958 when the Lewis Merthyr Colliery, located a few miles northwest of the Great Western Collieries, amalgamated with the Great Western operation and connected underground as part of a £1.2 million integration scheme. At this point, coal production ceased at the Lewis Merthyr surface facilities, with materials and supplies continuing to be supplied via Lewis Merthyr Colliery
Rhondda Heritage Park while coal extraction was redirected through the Tymawr shafts. The final phase of operations continued until 21 June 1983, when the last coal was raised at the Tymawr colliery, bringing to an end 132 years of mining operations that had begun with John Calvert's original Gyfeillion Pit in 1851. The colliery infrastructure was demolished soon after closure, though the Hetty Pit structures were preserved due to their historical and architectural significance. ==Post-closure and preservation==