Smidger was a reckless narrow-gauge engine who worked on the Mid-Sodor Railway.
According to Duke, Smudger was a show-off who rode roughly and often came off the rails. Duke tried to warn him to be careful, but Smudger never listened to his advice. He was finally punished by being turned into a generator and being put behind the engine shed.
No information was given about his fate once the Mid-Sodor Railway closed, so it must be assumed that he has either remained there, was shipped to a different place, or was scrapped.