The Flying Thistle arrived on Sodor as a visiting engine, Percy was the first to meet him, and the other engines did not think he was real at first, Bill and Ben once mistook him for Gordon, due to their similar appearances.
The Flying Thistle is based on an LNER Gresley Class A1/A3 locomotive. Gordon and Flying Scotsman are other members of this class.
The Flying Thistle is painted red with yellow lining and a crest on his tender, he also has a yellow plaque on his wheel arch with his name written on either side.
- In his first appearance, the Flying Thistle had a face, but in his second and final appearance, he was faceless.
- The Flying Thistle's name may possibly be a combination of the Flying Scotsman and the A1/A3 Pacific, Knight of the Thistle. Flying Scotsman became the only A1/A3 preserved, and Knight of the Thistle, later renamed to just Knight of Thistle in December 1932, was built in 1924 and entered service in August of that year, but was later withdrawn and sold for scrap in June 1964.