In May 1893 the “Glamorgan Free Press” informed its readers that “The Great Western Colliery” had surveyed the area halfway between Abertridwr and the Universal Colliery and that the company was going to sink on land owned by Lord Windsor!
The new Colliery was to be named after the landowner, Lord Windsor the Earl of Plymouth. Sinking of the North (downcast ventilation) shaft started in 1887 with the sinking of the South (upcast) shaft commencing in January 1898. On 3rd of June 1902, six sinkers drowned in the North Pit when the platform they were standing on tipped over and they fell into 25ft of water at the bottom of the shaft.
By 1913 it employed 2,246 men. It became a member of the Monmouthsire & South Wales Coal Owners Association. Amongst the directors were the Insole family of Llandaff, Cardiff who also owned other mines within the Rhondda Valleys. George Insole was a coal merchant operating in Cardiff in the 1840’s and was given a whole lot of credit for introducing Welsh coals into the important markets of London. His accumulated wealth from the selling of coal from the Merthyr Tydfil and Aberdare area enabled him to venture into mining and establish a family business that was to stay into coal mining until Nationalisation (1947). George Insole & Son were also the Sole Shipping Agents for Windsor Coal shipped out from Bute Cocks, Cardiff.
In 1925 Windsor Colliery was sold to the Powell Duffryn (PD) Steam Coal Company for £250,000.Which equates to almost £15 million pound today!
The PD showed their “gentle approach” to industrial relations by placing all the leading activists of the South Wales Miners’ Federation on the afternoon shift, and then a little later stopped that shift. All the afternoon shift men were then re-employed except for about thirty” hardliners”.
By nationalisation of the Nation’s coal mines in 1947 there were 162 men working on the surface and 701 men underground at the Windsor. This continued until a decision was taken that the new “show Pit” nearby, the Nantgarw Colliery would be able to produce 750,000 tons of coal every year out of an anticipated 176 million tons of coking coal reserves. However, the poor working conditions and industrial problems that arose at Nantgarw resulted in a vast turnover of manpower. The NCB announced that unless it showed a marked improvement within several months it would have to close.
The only way of saving Nantgarw was to close Windsor Colliery, transfer the workforce to Nantgarw and mine the Windsor’s coal from the new Pit. Work commenced on linking up the two Colliery’s underground. The final breakthrough happened in 1974 with the Windsor’s coal reserves transferred to Nantgarw in an attempt to get away from the difficult geology of Nantgarw. The surface buildings at Windsor Colliery were then dismantled. £1.7 million was expended on this project! After years of heavy losses Nantgarw finally started to make money. Aber Valley no longer had its Collieries! During the working life of the Windsor Colliery 156 men died at a result of accidents (including the six sinkers).