Bert is the quietest of the Arlesdale Railway engines. He is the oldest out of the engines including Rex, Mike, and himself.
Bert worked on an unnamed line in England until 1967, at which time it closed down and he, Rex and Mike were sent to Sodor to work the Arlesdale Railway. Some time after his arrival, Bert took offence when the Reverend W. Awdry and the Reverend Teddy Boston accidentally sprayed him with mud while passing him in their car, and in retaliation Bert drenched the Reverend Teddy Boston with water when he took a ride in Bert's cab. However, both parties made up and as a result, Bert was featured in the Reverend W. Awdry's next book, Small Railway Engines.
For a long time Bert had trouble with steaming, but this has stopped since he was rebuilt into a narrow gauge outline with a taller chimney, dome, cab, and a larger boiler in 1973, giving his current appearance.
Bert is friendly, and somewhat clever and cynical.
- Bert will meet Winnie the Pooh, Ash Ketchum, Mickey Mouse, Littlefoot, Simba, Tai, Princess Twilight Sparkle and their friends in Pooh's Adventures of Thomas & Friends: Sodor's Legend of The Lost Treasure and Tigger refers to him as "Berty boy".
- Bert will guest star in Thomas' Adventures of Fantasia.
- Bert will meet Emerl & his friends In Team Robot In Thomas and Friends: Sodor's Legend of the Lost Treasure
- Bert is best friends with Wensley.