Thomas the Tank Engine Wikia
Thomas the Tank Engine Wikia

Diesel 40125, nicknamed "Old Stuck-Up" by James, was a diesel engine who once visited the North Western Railway on loan from British Railways.


The Railway Series

BoCo was to show Diesel 40125 around, but when he saw steam engines in the shed he refused to go further and insulted the railway for keeping them in service. An angry BoCo left him outside while he went inside the shed himself, and a furious James nicknamed him "Old Stuck-Up". [1]

The next day, Diesel 40125 was about to leave when he remembered that he needed refuelling. He attempted to use BoCo and Bear's part of the shed to be refuelled and cleaned, but slid on the oily tracks and crashed into the back of the shed. He was sent home in disgrace after being talked to severely by the Fat Controller; BoCo noted that while he could not hear everything, he did not think it sounded particularly polite. [1]


Diesel 40125 is pompous, rude and arrogant like a lot of unfriendly diesels, and believes that steam power is inferior to diesel power. He soon made himself an enemy of the steam engines, particularly James who christened the nickname "Old Stuck-Up". BoCo, who was showing the diesel round, lost patience with him. In addition, he is described as being "particularly haughty" by the author.

Technical Details


Diesel 40125 is based on a British Rail (BR) Class 40 1Co-Co1 diesel-electric engine. Two-hundred members of this class were built from 1958 to 1962, and the last was withdrawn in 1985. They were given the nickname "Whistlers" because of the strange whistling noise their engines would make. Seven Class 40s are preserved at the National Railway Museum including D200, the first Class 40 ever built.

Diesel 782 and Class 40 are also based on BR Class 40s, hence the latter's name.

Unlike most diesel engines in The Railway Series, Diesel 40125's number is not fictional. The real 40125 was built in December 1960 as Diesel 325 and was the first member of the class built with "split" headcode boxes. It was withdrawn from service in May 1981 and scrapped at Swindon Works in December 1983.


Diesel 40125 is painted in the BR Rail Blue livery. He has yellow warning panels on his front and back end. His number (40125) is painted on the sides of his cabs in white. His rooftop is painted dark grey. His buffer beams are painted red with dark grey buffers.



  • The events of the story "Old Stuck-Up" from The Railway Series book, James and the Diesel Engines likely took place before the real 40125 was withdrawn from service in May 1981 and scrapped in December 1983.
  • In the fourth illustration of "Old Stuck-Up", Diesel 40125 is incorrectly seen in a lighter shade of blue.
  • Unlike most diesels from British Railways, Diesel 40125 does not have a BR crest or logo on his sides.


The Railway Series

Main Series


* RWS only | ** T&F only