Fergus is a railway traction engine.
Fergus mainly works at the cement works is thus called "the pride of the cement works".
Fergus knows the rulebook off by heart, and his catchphrase is "Do it right!" His insistence on doing everything absolutely according to the rules can annoy the other engines, but he is a decent engine at heart and will not hesitate to help others in trouble.
Fergus is based on the Aveling and Porter 2-2-0 'T9' class railway traction engine No. 9449 "Blue Circle", which is the only one left in the world. Since Fergus' introduction, "Blue Circle" has been dressed up as Fergus on special occasions on its home line, the Battlefield Line in Leicestershire.
Fergus is painted navy with gold boiler bands and red wheels.
- Fergus has never been seen with a fireman.