In the 1830's Thornley pit was sunk by Sir William Chaytor and Partners. The partners were Messrs. Thomas Wood, Rowland Webster, John Gully and John Burrell. The most famous was John Gully, known in his early years as a noted prize fighter, but subsequently he became a respected member of the House of Commons. Another claim to its fame, is that Thornley Colliery was sunk by the eminent engineer William Coulson. Coulson was one of the most well known colliery sinkers of his time who was responsible for the sinking of most of the pits in the Durham and Northumberland coalfield during the early 1800's. Born into a colliery family in 1781, William Coulson began his working career as a trapper boy in the pit, was and remained, uneducated. He came from a long line of miners and worked in collieries in the Gateshead area. He was a tremendously hard worker and self-made showing a genius for the work of winning new collieries and by energy, industry and perseverance, coupled to his skill of surmounting the most stubborn obstacles of nature, he became an engineer.
The first seam of coal, a little over 31 feet thick, was reached at Thornley on 29th January 1834 at a depth of 36 fathoms, and on the 21st March 1840 another seam, four feet thick, was struck 54 fathoms below the Five-Quarter. This was looked upon as an important discovery which gave rise to much rejoicing throughout the coal mining districts of Durham.
Thornley Colliery was the Centre of a great strike in 1843 (the year before the "big strike"). Warrants were issued against 68 of the workmen for absenting themselves from work without leave of their employers under whom they were serving on the terms of the yearly Bond. Mr Marshall, solicitor of Durham represented the owners; and Mr. Roberts of Manchester the "Pitman's Attorney General" defended. There was a long trial ending in defendants being committed to gaol for six weeks. Mr. Roberts however lost no time in obtaining writ and the men were removed from prison to the Court of Queens Bench where upon an informality being proved, they were acquitted.
Ludworth Colliery was the next to be sunk by the Thornley Coal Company and both of these collieries were sold to Messrs. Walton and Gowland in 1865 when a limited company was formed. Under new ownership, this company then sank the Wheatley Hill pit. It was a notoriously unreliable company and the three pits were the scenes of great excitement in the 1870's when the company didn't have enough money to pay its workmen. The Police from Castle Eden were forced to intervene to prevent a serious riot taking place with the men threatening to demolish the pit workings at bank as quite understandably, they were looking for retribution. The cashiers office had to be barricaded and the whole incident has become historical in East Durham mining circles and is always referred to as the "Putt Pay" - meaning that the pay day was put off. In fact it took many years for the men to recover the wages they lost during this incident. The three collieries stood idle for a considerable time - with Wheatley Hill and Ludworth becoming almost depopulated with the miners and their families moving away to find work in other pits. Long rows of houses were shut up at Wheatley Hill and grass and weeds grew almost knee deep in the streets.
Eventually, the Weardale Iron and Coal Company took over the ailing coal company operating Thornley, Wheatley Hill and Ludworth and in the course of time the pulley wheels were once more on the whirl and the deserted villages gradually assumed their former cheery aspect. The new owners made many improvements and after clearing Wheatley Hill pit of the water which had accumulated during the stoppage, they increased the depth of the shafts to the bottom seams. All the workings at bank were renewed, steel being substituted instead of wood in the heapstead and other erections, and appliances of the most modern kind were adopted. At this time, Wheatley Hill pit was considered to be one of the best equipped in the East Durham coalfield. The output of the three collieries was mostly consumed by the Weardale Iron and Coal Company with the surplus being shipped to the Hartlepool's.
The pits of Wheatley Hill, Thornley and Ludworth saw the best of times, when their coal was considered to be the best in the Durham coalfield and therefore sold for high prices and the worst of times when on more than one occasion the owners had no money to meet the wage bill. Nevertheless the collieries stayed in coal production - Ludworth until the 1920's, Wheatley Hill until 1968 and Thornley until 1972.