In 1866, the Pembroke and Tenby Railway was extended to Whitland; Whitland was on the South Wales Railway broad gauge main line but being on the narrow gaugelater known as standard gaugeit was not possible to run Pembroke and Tenby trains on the South Wales Railway lines to Carmarthen. The intention of the Pembroke and Tenby Railway was to make an alliance with other narrow gauge railways at Carmarthen, and the Great Western Railway (as successor to the South Wales Railway) did provide a narrow gauge link to Carmarthen. Experiencing financial difficulties, the company sold its line to the Great Western Railway in 1897.