The Sheffield, Ashton-under-Lyne and Manchester Railway was an early British railway company which opened in stages between 1841 and 1845 between Sheffield and Manchester via Ashton-under-Lyne. The Peak District formed a formidable barrier, and the line's engineer constructed Woodhead Tunnel, over three miles (4.8 km) long. The company amalgamated with the Sheffield and Lincolnshire Junction Railway and Great Grimsby and Sheffield Junction Railway companies, together forming the Manchester, Sheffield and Lincolnshire Railway in 1847.

Thomas Brassey was an English civil engineering contractor and manufacturer of building materials who was responsible for building much of the world's railways in the 19th century. By 1847, he had built about one-third of the railways in Britain, and by time of his death in 1870 he had built one in every twenty miles of railway in the world. This included three-quarters of the lines in France, major lines in many other European countries and in Canada, Australia, South America and India. He also built the structures associated with those railways, including docks, bridges, viaducts, stations, tunnels and drainage works.