The shunter is apparent to be explored more in a story titled New Wheels for Sidney in the upcoming new series where decorative lights and a cargo car are also involved. The pack is called Sidney's Holiday Special.
The discovery was found in a catalogue advertising official Wooden Railway merchandise. Sidney made a silent debut in Day of the Diesels and only ever appeared in three shots.
It is believed that his role was increased in an original version of the special before scenes were cut.
Thomas is to also have an episode to himself, wearing a red nose and an antler and hauling Father Christmas on a truck. Santa's Little Engine is the same title as its spin-off product.
The brand new seventeenth series of Thomas & Friends airs this fall.
Thanks to SI3DFilms for the alert.