- “There is a real engine like Rheneas. His name is Dolgoch and his home is at Towyn in Wales.”
- ―The Author, Gallant Old Engine
Dolgoch is Rheneas' twin and his real life counterpart.
Dolgoch was built in 1866 by Fletcher, Jennings & Co., but to a very different design to that of Talyllyn. He is a Class Bb 0-4-0 tank engine with both a back tank (behind the cab) and a well tank (between the frames). The long wheelbase allows the firebox to sit in front of the rear axle, with Fletcher's Patent inside valve gear driven off the front axle, a particularly inaccessible arrangement. In increasingly decrepit condition, Dolgoch continued to operate the service single-handedly until 1952 when Edward Thomas became available and was then the subject of a prolonged overhaul between 1954 and 1963.
Dolgoch returned to service in late 1999 after a major overhaul involving firebox repairs and an extensive mechanical overhaul; as part of the overhaul he has been fitted with air braking equipment, the last steam loco on the Talyllyn Railway to be fitted.
Dolgoch previously ran in his 1946 light green livery. Between 2011 and 2014, he ran in Crimson Lake livery. In January 2015, he and Talyllyn were repainted Indian red in honour of the railway's upcoming 150th anniversary.
Overhaul and Appeal
During Autumn 2009, the Talyllyn Railway booked Dolgoch for an overhaul. To ensure that Dolgoch was repaired by May 2011, which marked the 60th anniversary of railway preservation, "Steam Railway" magazine launched an appeal to raise funds for Dolgoch's next overhaul, which includes a new boiler to its original design. However, whilst the appeal was being made, an examination of Dolgoch showed that he had a crack in his rear tubeplate, which forced him to be withdrawn for overhaul earlier than expected. Luckily though, by January 2010, thanks to the readers of "Steam Railway" magazine, the Dolgoch appeal was so successful that the overhaul was able to commence. During the second week in February, Dolgoch was dismantled for the removal of his boiler from his frames. Then, his boiler was lifted from his frames on 23 February 2010.
On 22 March 2011, Dolgoch's new boiler, built in the Severn Valley Railway's Boiler Shop in Bridgnorth, was completed with a new smokebox and passed its steam test eleven days after. On 28 April 2011, the boiler was back at the Talyllyn Railway for Dolgoch's overhaul to be completed. Following completion of his overhaul, Dolgoch is now back in working service and attended the 60th anniversary of railway preservation on 14 May 2011.
During 2012, Dolgoch took part in the third annual Steel, Steam and Stars event at the Llangollen Railway where he ran on a dual-gauge length of track at Carrog station with the Ffestiniog Railway's Palmerston.
- Gallant Old Engine - Gallant Old Engine (mentioned in foreward)
- Very Old Engines - Crosspatch (mentioned) and Duck and Dukes (does not speak)
- 1979 - Annual
- 1980 - Annual
- 1987 - The Island of Sodor: Its People, History and Railways (mentioned)
- 2005 - Sodor: Reading Between the Lines (mentioned)
- His name means "Red Doll" in Welsh.
- Dolgoch was built at Fletcher, Jennings & Co. at Whitehaven, the same place where Skarloey, Rheneas, Talyllyn, and Captain Baxter were built.
- He bore the name "Pretoria" for a short while in the early 20th century in celebration of said city's relief during the Boer War.