Bert is the quietest of the Arlesdale Railway engines. He is the oldest out of the original three.
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 and cab in 1972. In 1976, he was rebuilt with a larger boiler, giving his current appearance.
Bert is friendly, and somewhat clever and cynical.