Since the 1860s trains have conveyed crushed limestone from Derbyshire to the soda ash and chemicals works in mid-Cheshire. By the 1930s a new higher capacity design of wagon was needed, and so the 'Hoppers' were built by Charles Roberts for Imperial Chemical Industries. The fleet of 152 bogie hopper wagons became instantly recognisable to railway enthusiasts. For just over sixty-one years between 1936 and the end of 1997 the wagons worked almost every day of the year, running several times per day. Modern wagons took over the duties from 1998 and the traffic still runs around six times per week, feeding the sole remaining soda ash plant. Many companies and locomotive classes and types have hauled these services since 1936 including the LMS, BR, Transrail, EWS, Freightliner Heavy Haul and now DB Cargo. The locomotives used include steam classes 4F, 8F and 9F; and diesel-electric classes 25, 37, 60 and 66.