 Construction began on the line on 8 September 1870 . It was built as cheaply as possible , using the cheapest available materials and winding around hills wherever feasible to avoid expensive earthworks . The station platforms were crude earth banks 6 inches ( 150 mm ) high , held in place by wooden planks . As the Duke intended that the line be worked by horses , it was built with longitudinal sleepers to reduce the risk of them tripping . 
