[1][2] The South Wales Railway Act also authorised a branch line from Whitland to Pembroke, taking a direct course and not running near Tenby.

Also, Brunel was having misgivings about Fishguard due to its exposure to high winds and the decision was taken to make a port on the north shore of the Milford Haven Waterway at Neyland instead, and to extend the planned Haverfordwest branch.

However, the South Wales Railway (SWR) did not attempt to build their Pembroke branch, so construction of the Tenby and Saundersfoot line was not started either.

[note 1][1][3][4] At this, the SWR undertook to introduce a new Bill for the line, and de Rutzen agreed to withdraw his writ.

In 1853, the SWR sought an extension of time for construction of the branch and a change to the route, taking it closer to Tenby.

When the South Wales Railway was first authorised, Pembroke was the most important centre in the area and the proposed branch was a natural asset.

Plainly, building a 27-mile railway from Whitland to Pembroke dock was unattractive, and in any case, the company had already stretched its finances too far.

Finally, the SWR dividend for the second half of 1857 was suspended; in the High Court; it pleaded that it had attempted in good faith to build it, but now had no money to do so.

[3] This was the last straw for the local people and they resolved to prepare their own bill for a line from Tenby to Pembroke Dockyard with a short branch to the pier at Hobbs Point for the ferry to Neyland.

On 21 July 1859, the line was given the Royal Assent and the South Wales Pembroke and Tenby Junction Railway was authorised.

It seemed likely that the company's plans were in vain, but the dynamic contracting partnership of David Davies and Ezra Roberts entered into discussions with the directors and on 4 July 1862 they committed to build the line and provide rolling stock for £106,000.

[5][4] During the construction process, the Directors had given consideration to extending the line to Whitland; the isolation from the national railway network was a limitation.

[1][5][6] The presumption that the Great Western Railway would acquiesce in mixing the gauge of the track from Whitland to Carmarthen proved to be naive; the GWR would not hasten to facilitate unwelcome competition in its own back yard.

The parliamentary bill for this was passed on 6 August 1866;[4] GWR opposition was in vain in view of its obstructive attitude; the act of Parliament[which?]

[4] The Pembroke and Tenby Railway Company contributed £20,000 to the cost of the GWR conversion;[7] they protested that they had assumed that both lines would be converted to mixed gauge.

[1][7] At this stage there was no P&TR passenger service on the line east of Whitland: the traffic was chiefly minerals and general merchandise.

In addition the P&TR had to negotiate with the Manchester and Milford Railway (M&MR) over access further north, and of course the GWR.

The C&CR demanded £350 annually for the use of Carmarthen station facilities, where P&TR goods traffic was exchanged with the M&MR and the Llanelly Railway.

[4] In May 1872, the LNWR published a timetable showing through carriages from Tenby to Euston, running via Shrewsbury and Stafford and in retaliation the GWR announced a Paddington to Pembroke Dock through connection via Gloucester.

From the same date, the Manchester and Milford Railway (M&MR) ceased to run into Carmarthen Town station, and it terminated its trains at Pencader; the through carriages from Euston were no more, and the P&TR was isolated from its earlier narrow gauge allies.

c. vi) had envisaged the ferry pier at Hobbs Point in Pembroke Dock being the termination of the railway line, giving direct access to Neyland.

[1][4][7] From 1874, earnings declined and, by 1877, the financial situation of the Pembroke and Tenby Railway (P&TR) was serious; moreover the state of the permanent way and other infrastructure was known to be poor, and money needed to be spent on it.

In 1886, the Board of Trade was critical of the P&TR practice of running mixed trains with passenger carriages behind the goods wagons.

The GWR absorbed the company on 1 July 1897, authorised under the Great Western Railway (Additional Powers) Act 1897 of 6 August 1897.

[1] The GWR had long been considering moving Carmarthen Town station to the south side of the River Towy, to a site where plenty of available land existed.

At the beginning of the twentieth century, there was a daily through-carriage from Tenby to Paddington and return, as well as a sleeping car to and from Pembroke Dock, but this did not survive World War I.

Diesel traction was first seen on the branch on summer Saturdays in 1959 and regularly from the autumn of 1963; the final steam train ran on 8 September 1963.

Trains stop (on request at some stations) every two hours in each direction, westwards to Pembroke Dock and eastwards to Tenby, Whitland, Carmarthen and Swansea.