- “I hope it's cold tonight and he can't start in the morning. At least someone might want to preserve us. Who'd need him? Old Stuck-Up!”
- ―James, James and the Diesel Engines
BoCo was to show the visiting diesel 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".
The next day, Old Stuck-Up was about to leave when he remembered he needed refuelling. He attempted to use BoCo and Bear's part of the shed to be refuelled and cleaned, but slid on cleaning fluid on the rails 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 couldn't hear everything, he didn't think it sounded particularly flattering.
Old Stuck-Up is rude and arrogant like a lot of diesels, and believes that steam power is subpar to diesel.
Old Stuck-Up is based on a BR Class 40 1Co-Co1. Class 40 is another member of this class. 200 members of this class was built from 1958 to 1962, and the last was withdrawn in 1985. They where given the nickname "Whistlers" because of the strange whistling noise their engines would make. Seven Class 40s are preserved, the first built, D200, at the National Railway Museum.
Unlike most diesels in the Railway Series, Old Stuck-Up's number wasn't fictional. The real 40 125 was built in December 1960 as D325 and was the first member of the class built with "split" headcode boxes. It was withdrawn from service in May 1981 and cut up at Swindon Works in December 1983.
Old Stuck-Up is painted in the British Railways' Rail Blue with yellow warning panels. His number, 40 125 is painted on the sides of his cab in white.
- Due to the real 40125 being scrapped in 1983, the setting of "Old Stuck-Up" likely took place before that date.