"Not bad. I've seen worse. At least you're all clean."
— The Diesel, Bowled Out, fourth season

The Diesel
  • Number: D261, originally D4711
  • Class: BR Class 40
  • Designer: British Railways
  • Builder: Vulcan Foundry
  • Configuration: 1Co-Co1

The Diesel, also known as Class 40D4711 (in the Railway Series) and D261 (in the TV series), is a Diesel who once came to the North Western Railway on loan from the Other Railway.


The Diesel is snobbish and rude, believing that Diesel engines should take over from steam engines.


The Diesel was built at the Vulcan Foundry in Newton-le-Meadows, Lancashire, England in the early 1960s. The Diesel was sent to Sodor in 1963 to assist the engines with goods and express work during Stepney's visit, but only insulted the other engines by saying they were out-of-date. He got his comeuppance when an inspector's bowler hat jammed in his air intake, leaving Duck and Stepney to take the Express for him.

While everyone was fare-welling Stepney, the Diesel crept away, leaving behind "a rather nasty smell and a battered bowler hat".


The Diesel is based on a BR Class 40 1Co-Co1. Another member of this class is Old Stuck-Up.


The Diesel is painted in British Railway's two-tone green livery with a black roof and yellow warning panels.


  • The Diesel's television series number is real. The real D261 was built in 1960 and withdrawn in 1983.