Three parallel veins of Ordovician slate run through mid Wales. These veins near the surface at three locations - around Abergynolwyn in the west, surrounding Corris, and at their easternmost in the district around Dinas Mawddwy. Each of these locations has been a centre for slate quarrying, although Corris was the largest producer of the three.
By 1854, the slate quarries at Dinas Mawddwy were employing a significant number of people. At the same time, a new Lord of the manor of Dinas Mawddwy was installed, Edmund Buckley. He sponsored the building of a railway to connect the slate quarries at Dinas Mawddwy with the recently opened Cambrian Railways main line, at Cemmaes Road.
The construction of the railway was contracted to R.S. Francis, with the contract starting in 1866. The railway opened on 1 October 1867. The first locomotive to work trains was Mawddwy which had previously been owned by Francis and used during construction. This was joined in 1868 by a second Manning Wardle locomotive, named Disraeli. Slate traffic and agricultural produce made up the bulk of the traffic on the railway, but from the earliest days it was clear that the railway company was struggling financially. In 1892 the Maes-y-gamfa slate quarry opened, connected to the Mawddwy Railway's Aberangell station via the Hendre-Ddu Tramway, bringing the promise of additional revenue. However by this time, the infrastructure of the railway was considerably worn and there was no financial revival.
The slate industry continued to decline during the late 1890s and early 1900s, and the Mawddwy Railway continued to run down as revenues did not allow effective maintenance. Passenger services were suspended "pending repairs" around 1900. A single daily freight train continued to run until April 1908, at which point all services were abandoned due to the poor state of the track.
The local community, led by David Davies, called a series of meetings with the aim of reviving the railway. A proposal to form a new light railway to take over and operate the Mawddwy Railway. In 1910 a Light Railway Order was granted, permitting the railway company to construct a "new" light railway on the disused trackbed. Reconstruction commenced immediately under the direction of G.C. MacDonald, the Engineer of the Cambrian Railways. The track was relaid in heavy rail and several bridges were rebuilt or strengthened. On 29 July 1911 the railway reopened under the chairmanship of David Davies, with trains operated by Cambrian Railways.
The advent of the First World War dealt a significant blow to the railway. Several local slate quarries closed and tourist traffic fell considerably, although timber and munitions traffic for the war effort offset this somewhat. After the war ended, the railway continued to struggle. In 1923 the Great Western Railway (GWR) took control of the Mawddwy Railway as part of the grouping of British railways. The GWR introduced buses to the Dyfi valley, many operated by its subsidiary the Corris Railway. These competed with the passenger services of the railway, leading to the end of passenger services at the end of 1930.
Freight services continued through the Second World War, although the local slate industry continued to decline. The quarries served by the Hendre-Ddu Tramway closed in late 1939, though part of the tramway continued in use to bring timber from the forests west of Aberangell. After the war, the railway became part of British Railways at nationalisation. In September 1950 heavy flooding of the River Dyfi damaged the railway bridge north of Cemmaes Road station. The line was officially closed on 1 July 1952. The track was lifted early in 1952.
|Name||Type||Builder||Works number||Date built||Cylinder size||Wheel diameter||Notes|
|Mawddwy||0-6-0 ST||Manning Wardle||104||1864||12 in x 17 in||3 ft 0 in||Delivered in 1865 to contractor R.S. Francis for use on construction of the Potteries, Shrewsbury and North Wales Railway. Sold to the Mawddwy Railway in late 1865. Rebuilt in 1893 and 1911. Transferred to the Van Railway after 1911, scrapped in 1940.|
|Disraeli||0-6-0 ST||Manning Wardle||268||1868||13 in x 18 in||3 ft 6 in||Slightly larger locomotive than Mawddwy, scrapped in 1911.|