Class 40, also known as The Diesel, D4711 (in the Railway Series), D261 (in the television series), or simply Diesel is a diesel who once came to the North Western Railway on loan from the Other Railway.
Class 40 was built at the Vulcan Foundry in Newton-le-Meadows, Lancashire, England. Class 40 was sent to Sodor in 1962 to assist the engines with goods and express work toward the end of Stepney's visit, but he only insulted the other engines by saying they were out-of-date, should be scrapped and bragged about his modernity. He got his comeuppance when an inspector's bowler hat jammed in his air intake, causing him to break down and to become as sick as boiler sludge. He sulked in the shed while Duck and Stepney took the Express for him.
While everyone was fare-welling Stepney, a disgraced Class 40 crept away, leaving behind "a rather nasty smell of bad manners and a battered bowler hat".
Class 40 is snobbish and rude, believing that diesel engines are superior and should take over from steam engines. Despite this, in the magazine stories, there are some occasions in which the Diesel is polite and helps out the steam engines.
Class 40 is based on a BR Class 40 1Co-Co1. Old Stuck-Up and D782 are also members of this class. 200 members of this class was built from 1958 to 1962, and the last was withdrawn in 1985.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. Over seven Class 40s are preserved with the first built, D200, at the National Railway Museum.
Class 40's television series number belonged to a real Class 40. The real D261 entered service on the 26th of February 1960 and in 1973 It was repainted into "RailBlue" colours and renumbered to 40 061 until the engine was withdrawn from service in 1983 and scrapped at Crewe in March the following year.
Class 40 is painted in British Railways' two-tone green livery with a black roof and yellow warning panels. In the television series, Class 40 is painted in British Railways' Brunswick green livery, with a thin, lighter green stripe running along his top and yellow warning panels. His number is painted on his cab sides in yellow.
In the Railway Series, his face was yellow, while in the Television Series, it was grey like the other engines.
- Michio Nakao (Japan)
- Class 40's Railway Series livery is inaccurate as none of the Class 40 diesels received British Railways two-tone green livery.
- Class 40 is called "Diesel 261" in Japan.
- According to some VHS descriptions for Bowled Out, Class 40 was brought to Sodor to take over Daisy's work while she was ill.
- His Hornby model depicts him as a Class 37 diesel which still has an inaccurate number for a locomotive of this type.
- His Railway Series number is completely fictional, none of the Class 40's wore this number.
- In the Days Out with Thomas events, Class 40 wore Toad's face.
- ERTL (discontinued)
- Wooden Railway (discontinued)
- Hornby (Re-used Class 37 Diesel tooling; labelled as Diesel D261; discontinued)
- Brio (discontinued)
- Thomas Engine Collection Series (discontinued)
- Nakayoshi (discontinued)
- Take-n-Play (labelled as Class 40; discontinued)
- Trading Cards (discontinued)
- De Agostini (discontinued)