Duncan is a grumpy narrow gauge engine.
Andrew Barclay and Co. Ltd.
Duncan arrived on the Skarloey Railway after Peter Sam's accident with the slate trucks. At first, he was bouncy and rude and "rock and rolled" along the line despite Rusty's warning. He continued to grumble about passengers and not being polished until Skarloey told him how Rheneas saved the railway, and learnt sense after that and was glad when Rheneas came home. Several years later, he helped get some drinks to some scouts on a very hot day.
He was prone to boisterous bouncing about, which became known as "rock 'n' roll", whenever the mood took him, which once caused him to derail in the mouth of a tunnel. He speaks with a Scottish accent and is a rather tall engine. He often grumbles and complains, usually about not being polished or being over-worked, and can be rude, rough, and bad tempered. He claims to be a plain-speaking engine who believes in plain speaking, an approach which can cause him to make callous or belligerent remarks. Duncan can be a competitive engine too, particularly with James. He can be careless and make rash decisions which usually leads to his own downfall, but is not always quick to apologise or realise the error of his ways. However, upon Skarloey recalling Rheneas's gallant act to get his passengers home, Duncan admitted he had the wrong attitude and tried hard to be a more useful, respectable engine in future. In spite of his ways, Duncan can be a little misunderstood as he is focused, confident, resourceful, and has a big heart.
He is painted golden yellow with black lining and gold boiler bands.
Adventures on Rails
- Season 12 - Centenary of the Skarloey Railway.
- Season 14 - Paxton and the Blue Mountain Quarry and Duncan's Dive.
- Season 17 - Rules and Regulations.
- Season 18 - The Spirit of the Blue Mountain Quarry, James and Percy.
The New Adventures on Rails
- Season 1 - Down the Bridge, Sir Handel and the Ghost Engine, The Old Warrior, High and Mighty, and Oldies But Goldies
- Season 2 - Coach Brakes, Rheneas and the Dinosaur, Paul and Rusty, and The Importance of Being Neville
- Season 3 - The Fastest Engine in the Hills (cameo), Skarloey and the Mountain Bikers, Don't Be Late!, and Luke and the Christmas Party
- Season 4 - Duncan and Victor
- Season 5 - Creepy Cutting and Smoke Signals
- Season 6 - Edward and the Express
The Adventures on Sodor
- Season 1 - Old and Wise (does not speak), Dashing Duncan, Sir Handel and the Coal Mines, Scottish Engines, Skarloey Comes Home, Rheneas' Risky Ride, Special Brakes, Rheneas' Risky Ride, and Rusty Rescue
- Season 2 - Trouble on the Line, The Return of Boulder, Duncan's Discovery, and The "Ghost" Warrior
The Many Adventures on the Island of Sodor
- Season 1 - Duncan in Love, Rock 'n' Rolling Again, Luke's Lucky Find (cameo), Old Engine, New Changes, and Duke Does it Again (does not speak)
- Season 2 - Arthur's New Route (cameo), Clean vs. Dirty, Peter Sam and the Lost Engine, and The Search for Neil (cameo)