Duncan was built by Andrew Barclay at Kilmarnock in 1918 and worked in a factory in Scotland, which Peter Sam claims is the source of his strong accent.
In 1958, Duncan was sent to Sodor to do Peter Sam's work after his accident with the slate trucks, and re gauged to 2ft 3in. Duncan was rude and arrogant at first, but was humbled after derailing while doing "rock and roll" and having to be rescued by Rusty, whom he detests for being a diesel.
But as the years went on, Duncan forgot what he had learnt, and in 1962 he stalled on a viaduct out of spite for not being polished. Skarloey finally taught him sense with the story of Rheneas' bravery and now Duncan is a Really Useful Engine.
Duncan is quite often bossy to the other engines about getting their work done quickly and thinks he knows better than them. Duncan still seems to ignore Rusty's warnings and advice until he lands himself into trouble. Also, Duncan tries to do the jobs which he thinks suits him well and he is quite competitive with James.
Duncan is based on the Talyllyn Railway's Douglas, approx. 15' 6", not to be confused with the standard gauge engine Douglas. This engine is currently selected to be dressed up as Duncan on special events associated with the "Thomas the Tank Engine" franchise.
In RWS, Duncan is painted in the Skarloey Railway's red livery with blue lining and his name painted in gold on his boiler.
Duncan is painted yellow with black and gold lining.
- Tom Stourton (UK/US; Series 18 onwards)
- Duncan got his buffers after arriving on Sodor.