Murdoch is one of Sodor's largest and strongest engines.
Murdoch is a BR Standard Class 9F used for fast and heavy goods trains. The class was the last of the BR Standards, and the final steam engine class built by British Railways, with the last one, "Evening Star," built in March 1960. "Evening Star" and eight other 9Fs are preserved. One 9F, "Black Prince" holds the record for hauling the heaviest steam-hauled train in Great Britain, at 2,198 tons.
Murdoch is painted orange with green and red lining. He has smoke deflectors, on which he wears red nameplates with gold lettering.
- According to early concept designs of the Season 7 characters, Murdoch was originally going to be a BR Standard Class 7. Also, after his 9F class was decided on, he was originally going to be maroon red with chrome yellow linings, according to Robert Gauld-Galliers' original art work. Because Arthur was already going to be maroon with yellow linings, Murdoch's livery was changed to orange with green and red linings so that the two engines' colour schemes would not clash with each other.
- In his concept art, he seems to have a double chimney, which were fitted on 9Fs built from 1958 onwards.
- Murdoch shares the same whistle sound with Arthur, which itself is a LMS whistle stock sound effect.