The line closed to passengers in 1962 although sections at either end were retained for a while to carry freight traffic.

The South Devon Railway (SDR) built its line from Exeter to Plymouth, opening to a temporary station at Laira Green on 5 May 1848.

It extended to its Plymouth terminus at Millbay on 2 April 1849 for passengers, with goods traffic starting on 1 May 1849.

c. clxxxix), on 24 July 1854, authorising construction of a 13-mile (21 km) line from Tavistock to a junction with the South Devon Railway east of Plymouth; the track gauge was to be the broad gauge, 7 ft 1⁄4 in (2,140 mm), and authorised capital was £160,000 with borrowing powers of £53,600.

As well as serving the connected communities, the line had the strategic purpose of blocking incursion by competing narrow gauge companies, sponsored by the London and South Western Railway (LSWR).

Anthony says There was period of anxiety in May, when it was rumoured that the House of Lords would compel the Company to introduce a clause for the narrow gauge to be adopted over the whole of the line, and even to carry it into Plymouth.

The chief engineer, A. H. Bampton, died a few months after the start of work, and the services of Isambard Kingdom Brunel were called in.

[3] The line was opened to passenger traffic on 22 June 1859, and for goods on 1 February 1860; it was worked by the South Devon Railway (SDR); trains from Tavistock joined the SDR main line at Tavistock Junction and ran to their Plymouth terminus at Millbay, a distance of 3½ miles.

c. cxi) empowered an independent company to extend the broad gauge line from Tavistock on to Launceston.

[2] Meanwhile the London and South Western Railway (LSWR) had been extending its westward route from Exeter, and with the intention of reaching Plymouth it encouraged a nominally local company, the Devon and Cornwall Railway (D&CR), to obtain powers to build a line to Lidford (called Lydford from 3 June 1897).

[7][8] The station at Lidford was in fact a two-platform terminus, and at first there was no rail connection between the D&CR and the former Launceston and South Devon line (now part of the SDR itself).

However under the clause inserted by Lord Reedsdale in the company's acts of Parliament, the South Devon was compelled to lay a third rail to make mixed gauge, so as to carry the LSWR's standard gauge trains over its line to Plymouth (the Millbay terminus and Sutton Harbour).

From 17 May 1876 LSWR trains ran from Exeter to the D&CR Devonport station over the SDR line from Lidford via Tavistock Junction.

Trains and rolling stock running from Plymouth to the Princetown line used the standard gauge rail, laid for the LSWR, as far as Horrabridge.

Another LSWR line reached Launceston on 21 July 1886, offering the town a more direct route to London via Okehampton and Exeter.

The Great Western Railway Leo class 2-4-0 was tried on the line before opening but found unsuitable.

However they were withdrawn from these duties after a high-speed derailment near Tavistock in 1898, following criticism by the Board of Trade inspector about the use of front-coupled locomotives on fast services.

[11] The Tavistock section of the line involved traversing difficult terrain, and there were six large viaducts on the route.

All built in 1859, from south to north they are: The viaducts were of the type classified as Continuous Laminated Beam.

The turnpike bridge was probably a King Through Truss, in which a timber A-frame provides the compression members, with wrought iron tie bars underneath; this design gives the best (least) depth of construction.

[10] From Millbay, trains for the branch left the Exeter main line at Tavistock Junction; towards Launceston was nominated the down direction.

[13] The junction was followed by The station at Marsh Mills near Plympton was opened to passengers on 1 November 1865 although "some form of passenger facility was provided from 15th March 1861 so that residents from the Plympton area could travel to Tavistock, principally for the Friday market".

Plym Bridge Platform was opened by the Great Western Railway on 1 May 1906 and was mainly used by people visiting the nearby countryside.

It was convenient for day visitors to the surrounding countryside, as well as for the villages of Clearbrook, Hoo Meavy and Goodmeavy.

The original buildings were of timber, but they were badly damaged by a fire in 1887 and were replaced by a stone structure.

A small engine shed was provided at the other end of the station, but this was no longer needed once the Launceston and South Devon Railway opened on 1 July 1865.

After 31 May 1890 the LSWR opened its independent line to Plymouth, running broadly parallel to the South Devon line as far as Tavistock, but crossing over; after Tavistock it diverged westward to reach Plymouth via Bere Alston.

[13] When the SD&LR line closed, the station continued in use for Southern Region trains until May 1968.

The goods yard was on the same side as the buildings but a private siding was opened in 1894 to serve a corn mill, and a factory was opened in the goods yard in 1917 that handled milk, and later made "Ambrosia" rice pudding.

The North Cornwall Railway opened a station adjacent as part of its main line, which crossed over the South Devon route east of the town.