The “Talyllyn” was the first locomotive delivered to the Talyllyn Railway before its opening in 1864. Today it is one of the oldest operational locomotives in the world and was only operated on this railway, although with short breaks. It had been built in 1864 by Fletcher, Jennings & Co. as a 0-4-0ST saddle tank with works number 42. Although it was a standard design of this company, it was the first to have a gauge of only 2 ft 3 in or 686 mm. It did not take long until it was found out that the very short wheelbase of only four feet led to bad running characteristics.

So it was sent back to its manufacturer in 1867 as soon as the second locomotive “Dolgoch” was ready to take over the work. Now “Talyllyn” received a trailing axle that was fixed in the rear part of the frames, increasing the wheelbase to eight feet. Soon the railway added a cab with a roof. It received new frames in 1900. When it became evident that the 79-year old boiler had reached the end of its life, the locomotive was withdrawn in 1945. In the following year, the quarry that had been the main reason to build the railway was closed.

Fortunately, when the Talyllyn Railway became a preserved line in the fifties, its oldest locomotive was brought to Gibbons Bros. Ltd. for a complete rebuild. This was done in 1957 and 1958 and after that, it continued to serve on its original line. With a new boiler that has a pressure of 160 instead of 120 psi, it was powerful enough for service until this day. After an additional overhaul that was begun in 2018, it is operational again since 2024.