Cambrian Railways owned 230 miles (370 km) of track over a large area of mid-Wales. The system was an amalgamation of a number of railways that were incorporated in 1864, 1865 and 1904. The Cambrian connected with two of the larger railways to give connections to the North West of England, via the London and North Western Railway; and with the Great Western Railway for connections between London and North Wales. The Cambrian Railways amalgamated with the Great Western Railway on 1 January 1922 as a result of the Railways Act 1921. The name is continued today in the route known as the Cambrian Line.
The earliest section of the Cambrian was the section from Three Cocks to Talyllyn Junction. This had been opened in 1816 as part of the Hay Railway, a tram-road worked by horses connecting the town of Hay with the Brecknock and Abergavenny Canal at Brecon. The western section was sold to the Brecon and Merthyr Railway; the eastern section became part of the Mid-Wales Railway (see below).
In the following list the dates are: date of incorporation; opening date
(The information in this section was taken largely from The Railway Year Book 1912.)
The Cambrian had connections with many independent lines, including:
The headquarters of the Cambrian Railways was at Oswestry railway station (Welsh: Croesoswallt). The building still stands today, although detached from modern network main railway lines, and was in use for commercial purposes until 2004. After restoration in 2005, this building was reopened as the Cambrian Visitor Centre in June 2006; but on 11 January 2008 closed due to the terms of the lease not being settled. It has since reopened and, amongst other things, is now (2009) being used as the headquarters for the newly formed Cambrian Heritage Railways (CHR) restoration project.