Duck is a hard-working and fairly large tank engine who heads up the Crotoonian Seaside Railway. Being the "poster engine" of the railway, Duck is often put in charge of headlining passenger duties and heavy goods work along the branch. He has an admirable and influential work ethic and doesn't let bigger engines bog him down. His insistence of following "The Great Western Way" can bother some of the engines, but they do know he means well and is still a very valuable friend.
While not featured in episodes proper so far, he has been seen doing a great deal of activity around the lines. He was seen shunting goods wagons at Celgreb Bay Harbour during Gordon and Farnsworth's dockside bickering, and off running light engine (presumably after delivery freight cars) at Cliffstone Junction.
Duck is based on a Great Western Railway 57xx Class 0-6-0 pannier tank engine with added sand boxes.
Duck is painted in the North Western Railway's green livery, unlined, with a green safety valve cover and black wheels. The number "8" is painted on each side of his cab in yellow, upon a black background with a yellow border.