[3] During the 1960s, he worked with Gerry and Sylvia Anderson as a special effects technician on series such as Thunderbirds, Captain Scarlet and the Mysterons, Joe 90, The Secret Service and UFO.

[2] He began working as a special effects technician on a series of programmes created by Gerry Anderson's AP Films that used a puppet technology called supermarionation.

[2] Mitton was a member of the supervising visual effects director Derek Meddings team, displaying a special skill in setting up the electronics necessary to blow up buildings on cue in Thunderbirds (1965–1966), Captain Scarlet and the Mysterons (1967–1968), Joe 90 (1968), The Secret Service (1969) and UFO (1970–1971).

[citation needed] Mitton directed 180 out of 182 episodes of the seven series made between 1984 and 2003, as well as writing the scripts once the show began to deviate from adapting Awdry's work in 1991.

[1] Mitton was able to move each engine's eyes in real time – not stop-frame animation– by using a radio control linked to a motor mounted behind them, and there was a sculpted mask that could be changed to give different facial expressions.

[1][2] The show became an instant success on British television, and in 1989, Allcroft helped created Shining Time Station (1989–1995) in the United States on the Public Broadcasting Service.

In 1989, inspired by the success of Thomas & Friends, Mitton and his new company, Clearwater Features, produced a new children's television series called TUGS, which lasted for thirteen episodes.

TUGS remains popular online and has an exhibition at the Midland Railway which preserves concept art, extended episode cuts, and the original models.