"Devious" Diesel is a British diesel shunter who works at Gridinia Bay Harbour.
Contrasting Piper's wide-eyed and friendly attitude, "Devious" Diesel is cynical and often out to serve himself. A trickster and an "average shunter", Diesel is a rather oily schemer who views diesels like himself as superior and "highly modern" compared to "claptrap" steamers. Of course, his arguments fall on deaf ears today with how friendly most steam engines and diesels get along, in addition to his outdated build, but he often tries to prove others wrong with his malicious scheming. Though he does want to show he's really useful, it's his way of going about it that's rather skewed.
Diesel is based on a BR Class 08. Over seventy members of this class survive today in preservation, while around 100 remain in service on the national rail network. They were in fact the most successful shunting engines in the world, with 996 of them built. Arry, Bert, Splatter and Dodge are also based on this class.
Diesel is painted in the British Railways' black livery. His livery originates from British Railways in the 1950s, during the time when all shunting engines were painted black. His side rods are black.