Coal was found in the Lydden valley near Deal on December 12th, 1912 at 1476ft. After WW1, Dorman Long & Co purchased mineral rights to large areas of land in the Deal area. Kent coal burned very hot, making it suitable for the Steel Industry and the company wanted their own supply. Shortly after, they joined forces with another company, Messrs. S. Pearson & Sons (who had built the Admiralty Harbour at Dover), to form Pearson & Dorman Long Ltd. This company had a controlling interest in the Channel Steel Company which had proved the existence of 100 million tons of iron ore near Dover.
They built a railway line to the site of their new Colliery, and the first shaft was cut on May 19th, 1924. It was planned to sink collieries at Wingham, Fleet, Woodnesborough, Stodmarsh and Deal.
Betteshanger was the biggest Kent mine, with shafts of 24ft (7.3 metres) diameter. It flooded twice during sinking, but using the cementation process to seal the shaft sides, the pit progressed quickly and reached coal in 1927.
Deputies' houses were built close to the pit but it wasn't until 1929 that the farmlands of Mill Hill on the outskirts of Deal were acquired for a new colliery estate.
Betteshanger attracted a lot of the hard-line union men blacklisted in their home areas after the General Strike of 1926. Consequently, the Betteshanger miners were often regarded as the most militant in Kent.
In 1938 a strike was called when some of the pit boys refused to accept the behaviour of the two deputies responsible for their supervision. Later in the day, the rest of the pit boys, and all the Colliers joined them, mainly because the pit could not run properly without the pit boys. Work was only resumed after agreement was given to hold a public enquiry.
Betteshanger was the only pit to strike during the Second World War, over allowances for working a difficult seam, where the conditions changed from week to week. This resulted in three union officials being imprisoned and over 1000 men being given the option of a fine or hard labour. There was danger that the strike would spread to other mines and the Government couldn’t afford a strike in the middle of a war. All but nine refused to pay and in the face of having to find prison spaces for 1000 men, the government decided to take no action and also to release the three imprisoned officials.
Betteshanger was the last colliery in Kent, closing in 1989.