Bertram is a narrow gauge engine who is known as "The Old Warrior." He was first released in the Bertram with Scrap Cars pack, and was later reintroduced individually to sell off excess stock.
- Learning Curve
- 2000 (tank engine, gold handrails, the letter L painted on his saddletank in black, and red cab roof)
- 2012 (cab ledge removed)
- 2016 (silver handrails, nameplate on saddletank, longer magnet guards, brown cab roof, cylinders, thicker funnel, new face, and added tender)
- In the television series, Bertram's characer was Duke's model repainted, wearing Smudger's face due to budget issues. However, according to Britt Allcroft, he was initially intended to be a tank engine. It is likely that Learning Curve was told he was a tank engine and was already producing his model before the change was made.
- Bertram's original prototype had a different, smaller face, a lower boiler, and a rounder cab roof.
- Bertram's 2016 model was the first one to actually match how he appeared in the television series, as it included a tender, nameplate and a more accurate face. However, Bertram still had his coal bunker and saddletanks that didn't extend to his running board.
- Bertram's first 2016 prototype was an altered version of his 2000 model, with the new livery and details. Its tender was an altered version of Ferdinand's.
- Bertram's second 2016 prototype had a different face from the final production model.