 One of the worst mining disasters in British history occurred at Gresford Colliery in 1934 when underground explosions and a subsequent fire cost the lives of 266 men.However the industry went into decline after the First World War, and of the seven large-scale collieries operating in the Wrexham area in 1946, only two functional collieries remained by 1968.The last pit to close in the Borough was Bersham Colliery in 1986.