S4C is a Welsh-language television channel. It was launched on 1st November 1982 and became the first channel aimed at a Welsh-speaking audience.

The channel aired the Welsh dub of Thomas & Friends, starting in 1986 as part of the "Clwb S4C" block and continues to air on this day, on the Cyw block. Thomas & Friends is known as Tomos a'i Ffrindiau and Tomos y Tanc a'i Ffrindiau in Welsh.

They also took over the Welsh dubbing of the series in the third series.

In April 2023, the channel began airing Thomas & Friends: All Engines Go.

Airings