The Great Western Railway was a railway company that was dominant in West Wales, in the United Kingdom. The main line from Swansea to Neyland, a port on Milford Haven Waterway, was opened as a broad-gauge line by the South Wales Railway from 1852, and that company merged with the Great Western Railway in 1862. The main line was converted to "narrow gauge" (later known as "standard gauge") in 1872, and most of the original main line is in use today.