Cambrian Railway Memo showing company seal 1892
The Cambrian Railways Company was formed by Act of 25 July 1864, which amalgamated the Llanidloes & Newtown Railway (4 August 1853), Newtown & Machynlleth Railway (27 July 1857), Oswestry & Newtown Railway (26 June 1855), and Oswestry Ellesmere & Whitchurch Railway (1 August 1861). The dates within brackets refer to when each company was incorporated. The Act included agreements with the Mid Wales and Manchester & Milford companies, and mutual traffic facilities with the Great Western Railway. A separate Act confirmed London & North Western Railway agreements. The Aberystwith & Welch Coast Railway (22 July 1861), was vested into the Cambrian Railways on 5 July 1865 by the Cambrian and Coast Railways (Amalgamation ) Bill.
The Cambrian worked the Mid Wales Railway from 2 April 1888 and absorbed the company by Act of 24 June 1904. It worked the dormant Van Railway on behalf of the owners from 1 August 1896, and the Wrexham & Ellesmere Railway, the Welshpool & Llanfair and Tanat Valley Light Railways from their openings on 2 November 1895, March-April 1903, and 5 January 1904 respectively, taking the TVLR over in 1921. The Cambrian promoted a Light Railway Order dated 2 March 1910, to reconstruct the derelict Mawddwy Railway and reopened the line on 29 July 1911. In August 1913 the Vale of Rheidol Light Railway sold out to the Cambrian.
The Cambrian Railways enjoyed a close relationship with the London & North Western Railway with which it connected at Whitchurch and Welshpool, operating through carriage services from Aberystwyth to London (Euston), Manchester (London Road) and Liverpool (Lime Street). In contrast the Great Western Railway had a Paddington to Barmouth through carriage via Ruabon and Dolgellau throughout the year. In summer the LNWR also had a service from Barmouth via Welshpool, and one from Pwllheli and Portmadoc via Afonwen Junction on the Coast Line. The GWR also had a summer service from Pwllheli and Barmouth via Dolgellau and to Aberystwyth via both Welshpool and the Manchester & Milford line. The Cambrian Railways operated a South Wales Express to Cardiff, Newport and the Rhondda via the Mid Wales and Brecon & Merthyr Railways, and in conjunction with the Taff Vale and Rhymney Railways.
The Cambrian was absorbed into the Great Western Railway in 1922 under the Railways Act of 1921. In its last year the Cambrian Railways sustained its worst accident, the head on collision that occurred between Newtown and Abermule on 26 January 1921 which killed seventeen people, including Lord Herbert Vane-Tempest, a Director of the Cambrian Railways Company.