In the 1980s, the Skarloey Railway bought two worn out Hunslet Diesels from the National Coal Board and using parts from both engines, constructed one good engine; Fred. He was put into service in 1989 as a secondary diesel and is used exclusively for maintenance and engineering work.
Once a year, Rusty and Fred have to pull a slow train that spreads weedkillers on the tracks. One holiday weekend, Fred was supposed to pull the weedkilling train, but fell ill, forcing Rusty to do the job instead. For unknown reasons, he did not attend Ivo Hugh's naming party.
Very little is known about Fred. It is assumed he is lazy and tries to stay out of work by pretending to be ill, but it is possible that he legitimately does fall ill often. Rusty once had to pay the price in New Little Engine.
Fred is based on the Talyllyn Railway's "Alf", an 0-4-0 diesel engine with a maximum speed of 9mph. Like Fred, Alf was built out of parts from another diesel engine, the spare engine being stored at Brynglas.