His death was announced by Michele Fabian-Jones, one of Mitton's partners in the children's television production company Pineapple Squared Entertainment, The New York Times said. Mitton, a native of Edinburgh, Scotland, directed or wrote more than 180 episodes of "Thomas the Tank Engine," dating back to 1984. Originally called "Thomas the Tank Engine and Friends," the show's name was later shortened to "Thomas and Friends" for British television.

It made its debut in the United States in 1989 as "Shining Time Station" on PBS. "He was a fanatic about planes and boats and obsessed with comedy shows," Fabian-Jones told the Times. "That's where it all started."