The 8½ mile long line ran from Clynderwyn (formerly Narberth Road) on the Great Western Railway via Maenclochog to Rosebush in the Preseli Mountains with its terminus at Rosebush. Founded by retired banker Edward Cooper, who had just brought a slate quarry in Rosbush. The company was bought by the North Pembrokeshire and Fishguard Railway in May 1894.