The stories take place on the fictional Island of Sodor.
Sodor is an invented island in the Irish Sea, positioned in the Railway Series’ imagined geography between England’s Cumbria and the Isle of Man. It is the home of Thomas, the other locomotives, and the railways controlled by Sir Topham Hatt, commonly called the Fat Controller.
Wilbert Awdry and his brother George created extensive details for Sodor, including its history, geography, industries, place-names, and fictional language. Their background work was later collected in The Island of Sodor: Its People, History and Railways, published in 1987.
Sodor is not the Isle of Man, despite the similar setting and Manx-inspired names. Skarloey is an engine and railway name, not the island’s name, while Lundy is a real island off the coast of Devon. Notable Sodor locations include Tidmouth, the island’s largest town, and Ffarquhar, the terminus of Thomas’s branch line.