This 0-4-2ST was built in 1921 by Kerr, Stuart & Co. Ltd. for use on the Corris Railway, and was purchased by the Talyllyn in 1951 – being named “Edward Thomas” after the TR’s former manager. After repairs carried out by the Hunslet Engine Co., the engine entered service on the Talyllyn in 1952 and has proved most successful. From 1958 until 1969 a Giesl ejector was fitted instead of a conventional chimney, the first such installation in the British Isles.
No.4 has run almost uninterpreted since 1952, with the longest time spent out of traffic in one go being three years. In 2004 an extensive overhaul was completed, which included the fitting of a brand new boiler.
“Edward Thomas” re-entered service in July 2024 after a short overhaul at the Vale of Rheidol Railway in Aberystwyth, returning in a striking grey livery – based upon the works livery of builder Kerr, Stuart & Co. Ltd.
The name “Edward Thomas” is not currently carried in this livery to emulate the loco’s earliest days on the Corris Railway, where it wore a similar grey livery for a short time.
CURRENT STATUS: Operational
| Maker | Kerr Stuart & Co. Ltd. |
| Year | 1921 |
| Works number | 4047 |
| Type | 0-4-2ST |
| Driving wheel diameter | 2′ 0″ |
| Trailing wheel diameter | 1′ 4″ |
| Coupled wheelbase | 3′ 0″ |
| Total wheelbase | 7′ 6″ |
| Cylinder size (bore/stroke) | 7 1/8 x 12″ |
| Heating surface | 115 sq. ft. |
| Working pressure | 160 psi |
| Tractive effort @ 85% BP | 3450 lbs |
| Weight | 9 1/4 tons |
| Length over buffers | 16′ 8″ |
