|Basis: Douglas, a locomotive from the Talyllyn Railway|
Duncan works on Mr. Percival's Narrow Gauge Railway. He means well but will "Rock 'n Roll" along the rails whenever the mood takes him. Duncan has a great big heart but is a little misguided.
- Duncan is the tallest of the narrow gauge engines.
- He is based on a narrow gauge, industrial tank engine built in Scotland at the time of the first World War.