A scheme to link Carmarthen with a proposed deep-water port in Cardigan found form as the Carmarthen and Cardigan Railway; a troubled scheme which opened in stages (hindered by the challenging topography of the Gwili valley and the sheer expense incurred in the construction of the Pencader Tunnel).

Despite progressing to the point where the project received an authorising Act of Parliament, the scheme never became a reality and the extension remained unbuilt.

[2] The corresponding Act of Parliament combined the authorising of both the sale of the undertaking with re-authorising the construction of an extension to Newcastle Emlyn.

[3] Preparations to extend the line beyond Llandysul remained slow; only by March 1890 were the Great Western Railway inviting tenders for the construction contract.

[13] Eventually, a Light Railway Order was acquired and the trackbed, between the sites of Llandysul and Newcastle Emlyn stations, was purchased.

[18] By 2014, the railway had suffered a loss of trained and managerial personnel, as well as volunteers essential for the line's operation.

The condition of the railway declined to a state where an Office of Rail Regulation (ORR) inspection raised significant concerns about the safety of the track.

In response, the licensee lifted the track between Henllan and Pontprenshitw and ran a 'land train' (tractor-hauled carriages).

[19] Site repair and rejuvenation and track relaying between Henllan and Pontprenshitw was restored to the satisfaction of the ORR and railway operations re-commenced in August 2020.

When the full length of the narrow gauge line was operational between Henllan and Llandyfriog Riverside, the route progressed westwards through forest lands before emerging onto an embankment on the northern side of the Teifi Valley.

The trackbed eastwards from Henllan Station is also owned by the Teifi Valley Railway company for several miles including Alltcafn tunnel (166 yards) and the Alltcafn gorge as far as the site of the former Pentrecourt Halt, this remains subject to future restoration plans.

This route avoids the need for major bridges, but required lengths of embankments and cuttings as well as one short tunnel.

These remaining two sections of the original Great Western Railway (between Pont Goch and Newcastle Emlyn; and between Pentrecourt Halt and Llandysul) are less likely to see future restoration, as the removal of original railway bridges crossing the Teifi mean that they are severed from the alignment on which the narrow gauge line has been built.

For the sake of clarity, this section will describe the route of the narrow gauge line when fully operational prior to 2014.