The Oaks explosion, which happened at a coal mine in West Riding of Yorkshire on 12 December 1866, remains the worst mining disaster in England. A series of explosions caused by firedamp ripped through the underground workings at the Oaks Colliery at Hoyle Mill near Stairfoot in Barnsley killing 361 miners and rescuers. It was the worst mining disaster in the United Kingdom until the 1913 Senghenydd explosion in Wales. Oaks Colliery The first shaft at the Oaks Colliery was sunk in the early 1830s. In 1845 two separate explosions occurred at the colliery. On both occasions few men were below ground and no more than three or four workers died. Two years later a more serious incident occurred after firedamp, which had accumulated in old workings, was ignited and exploded. Of the men underground, 73 were killed and 26 were rescued. Changes were then made to the colliery's ventilation. The downcast shaft was converted to upcast with a furnace at its foot. Two abandoned shafts were deepened to the lower seams and brought into use as the downcast and drawing shafts. The upcast shaft was close to the Dearne and Dove Canal and the downcast shafts were adjacent to the railway. The colliery covered about , of which two-thirds had been worked out. It was worked on the longwall principle, there being about of wall at the time of the 1866 explosion. The Barnsley seam is about thick. It is below the surface at the pit bottom, but dips significantly, so that it reaches . The Barnsley seam tended to experience outbursts of firedamp, and they were sometimes powerful enough to extinguish the Geordie lamps that were used at the time. On one occasion all the lamps for were extinguished. Gas built up in the uneven levels, and the goaves were full of firedamp. The air circuit was more than long. The induced draught was obtained from a pair of furnaces from the upcast shaft. At the inquiry after the explosion, it was pointed out that the colliery had not been visited by government inspectors for some years. The Oaks Colliery workings became part of Barnsley Main Colliery, which closed and re-opened several times between 1929 and 1966. Linked underground to Barrow Colliery, the No.2 shaft was used for man-riding in the 1970s. Production at Barnsley Main ceased in 1991. The colliery's winding engine house and pit-head structures are