Wow! You put out the fire!" "That's what my water cannons are for." "They are incredible! You are incredible, Belle! And so is your bell!" "Oh, thank you!

*Belle is a large blue tank engine fitted with water cannons. She is a member of the Search and Rescue Team.

Belle is a bold, big, blue tank engine, who is fitted with two water cannons atop her tanks, from which she can shoot water to fight fires. She also has a whistle and a big brass bell. Belle is lively, loud and proud, with a big personality. While she may come across as bolshy, highly self-assertive and overwhelming, Belle will always have the best of intentions at heart. She always wants to do her best and be the best she can be, causing her to be daring, energetic and bursting with enthusiasm. But Belle is happy to talk to any engine or vehicle and, although she may be quick to jump in with her own ideas, she always tries to understand, help and be kind to others. As a result, she is a very likeable engine; even Cranky gets on with her, she gets on well with Thomas and can even hold a civil conversation with Diesel. But she works especially well with Flynn, when helping him to tackle fires and is always there to support him should he make a mistake. Although fighting fires is always at the top of her list of priorities, Belle has also been known to perform goods duties about the railway.

Belle is based on a British Railways Standard Class 4MT tank engine with added water cannons, brass bell, and electric headlamps. These tank engines were a development of the LMS Fairburn 2-6-4T and were used for commuter and outer suburban services. They were used on all regions of BR, except the Western Region, and remained in service until 1967. Fifteen of these engines are preserved, three at the Bluebell Railway. Unlike her basis, Belle has a much longer and much thinner smokebox.

In real life, Belle's number, 6120, was carried by a GWR 6100 Class. One of these engines, 6106, survives in preservation.

Belle is painted royal blue with red and gold lining and brass fittings. She has the number "6120" painted in gold on her side tanks and a coat of arms consisting of a flame, two dolphins and a crown painted on her bunker sides. Her water cannons and wheels are painted red, with the latter having blue rims.*