- "Never give up! Never surrender!"
- ―Bertram, The Old Warrior
Bertram is a brown tank engine that works on the Skarloey Railway by the Mine Junction.
Bertram spent many years lost and forgotten in an old mine close to the abandoned Scottish Castle. It was Toby, The Fat Controller, and his grandchildren that eventually discovered the Old Mine where he had been in isolation. Toby, who was put on guard later in its restoration, found the "Old Warrior" resting close to an old warehouse. After that, Bertram was swiftly put back into service. He now works happily on the Skarloey Railway, working in the mines and quarries just like in his heyday.
After being rescued, Bertram was overjoyed, but never ceased to express his joy in his daily routine. He became so rambunctious and rowdy, that by the time Toby came to visit him at his new workplace, the other engines were becoming incredibly exasperated. After spoiling one of Duke's passionate tales about Smudger, the other engines began to express how fed up with Bertram they were becoming. It was not until Bertram rescued Toby from a collapsing High Tower that the other engines began to take him seriously.
Bertram's runaway cars caused a gunpowder shed to explode, much to Duke's dismay.
Bertram is repeatedly told to be quiet during several meetings at the Skarloey Railway sheds, due to the sheer poetic nature of his contributions to conversation.
Bertram was of very little help when Butch broke down and needed assistance.
Bertram nowadays works at the Blue Mountain Quarry. He also often works at Crovan's Gate Yards. He originally worked at the mine, but that was before Sir Frederick Aura blew it up along with Walter Sliggs' refinery.
During the fiasco with the Actor, Bertram demonstrated his knowledge of Shakespeare, which prompted the man to have the Skarloey Railway itself to enact a production of Hamlet, with the Thin Controller putting Bertram in charge of directing the play, much to the disappointment of the other engines (Except for Luke, who had decided to avoid the play by hiding in a tunnel). He takes his job quite seriously, fervently going about his duties to insure the production is a success. When the show ends on a sour note however, Bertram commends each of the actors for their strong performances on stage.
While working at the Blue Mountain Quarry, Bertram begins reciting spoken word poetry, much to the annoyance and or enjoyment of those around him.
Later, when Rusty broke down, Bertram was sent to retrieve him, and had to be silenced several times as he continued his dramatic speeches. While Rusty was being repaired, Bertram took over maintenance work on the railway. However, later on, Rusty was infuriated that the passengers had taken no notice of the repaired line and instead griped about the wind turbine at Strawberry Grove.As Bertram tried to give Rusty encouragement in one of his quotes, Rusty snapped at the Old Warrior, giving him even greater reason to be concerned. On his last maintenance run, there was a bump on the line that turned out to be a jagged rail pointing at the windmill at the grove. Bertram noticed this, but did not inform Mr. Hugh, instead, making a plan to destroy the windmill in order to restore Rusty's honor. Bertram gathered many truck from the Blue Mountain Quarry, intending to use himself as a battering ram to destroy the windmill, ignoring how doing so would kill himself! Laughing like a mad engine, Bertram charged at the windmill, with Rusty chasing after him! Rusty managed to brake the train as it derailed, preventing Bertram from sacrificing himself. In the end, Bertram bemoaned how he couldn't help Rusty feel appreciated, only for Rusty to apologize for snapping at Bertram, and stating how Bertram's, rather, strange scheme, did let him know that his work was appreciated, causing Bertram to burst into tears of joy, asking his driver for a handkerchief.
Bertram is passionate, jolly, enthusiastic, hard-working, poetic, intelligent, and certainly has a way with words! He is fond of the works of Shakespeare and alliterative language. Despite his enthusiasm, he can be a bit of a buzzkill, and Sir Handel and Duke in particular have very little patience for him. Despite everything, Bertram is a kind-hearted soul who only wants to make the best of each and every day he is in steam, because he remembers how lonely it was being stuck in a mine all by himself! He will try everything he can to help his friends, even concocting insane schemes and laughing insanely in order to do so!
- Season 1: The Old Warrior, Double Whammy, Cannon Fodder (cameo), Greg and Lars (cameo), Conspiracy Theory (cameo)
- Season 2: Breakdown Blues, Two Hearts Burn Together, Scot-free (cameo), Mavis and the Tornado (cameo), Rosie, Just Another Wild Goose Chase, Munitions (cameo), Blunderbuss, Swan Dive (cameo), Luke and Millie's Blue Mountain Adventure, Aura of Menace, All the World's a Stage, Swashbuckler, Thomas and the Fortune Teller
- Season 3: This Too Shall Pass (cameo), Chivalry is Dead, Percy and Asbestos (cameo)
- Bertram appeared in the promotional video about Troublesome Trucks voice acting along with the new model of Duck.