Donald and Douglas are Scottish twin engines. 



Season 1 - Lift Bridge, Swagger and SwervesThe Old Warrior, Bon Voyage (Donald only, cameo), Improvisation (Donald only), Rising to the Occasion (Douglas, mentioned), Buffer Bashing (Donald, does not speak), Scruff's Scaffolding, Wilbert the Lumberjack (cameo), Will Power (Donald only), Sidney and Conspiracy Theory (stock footage, do not speak).

Season 2 - Paxton and Norman (Douglas only, cameo), Rosie (episode) (cameo), Scot-Free (Douglas only), Pummeling Percy, Swan Dive (Douglas only; cameo)