"The Small Controller"
Mr. Fergus Duncan, nicknamed the Small Controller is the controller of the Arlesdale Railway. He is actually taller than the Fat Controller and the Thin Controller (Mr. Percival in the television series); his nickname refers to the fact that his railway is often called the "Small Railway".
He was appointed by the Fat Controller, the Thin Controller, and the Owner to run the line so they could get the supplies of ballast that reside in the hills on the line.
The Small Controller is very passionate about his work, and never married. He preferred instead to devote his life to work on his railway.
Fergus Duncan's attire consists of a yellow waistcoat over a white shirt with a red tie and a brown jacket over it, with mustard windowpane chequered trousers. He wears a yellow flower on his jacket.
- Unlike Sir Topham Hatt and Mr. Percival, he is referred to by his nickname in the US version of the television series.