The story of Duke being rediscovered was based upon a true story about Coronel Church, an engine abandoned in the Brazilian rainforest. The second source that inspired Sleeping Beauty was the rescue of the Cadeby Light Railway's Pixie by Teddy Boston.
Duke's affectionate nickname of "Granpuff" that was given to him by Stuart and Falcon was the same affectionate nickname Wilbert Awdry was given by his grandchildren due to their observation of smoke coming from his pipe looking like that of a steam engine.
Behind the Scenes
The Reverend Wilbert Awdry built an OO9 scale model of Duke (known as "The Duke") for his layout of the Mid Sodor Railway. Duke's model was donated by Awdry and put on display at the Reverend Teddy Boston's Cadeby Light Railway in Cadeby, Leicestershire, before the railway finally closed in 2005.
Series 4 model
Duke's main model was custom built to run on O gauge track to the Gauge 1 Scale Standard. Eight different facial expressions worn by Duke on screen. The faces were first sculpted in clay, and from that resin casts were made of a silicone mold. The model had a motor to power it mounted inside the chassis as well as an eye mechanism. The eye mechanism used servos mounted in the cab, the servos were hidden by blacking out the cab doors and windows. Metal rods went from the servos in the cab to a bracket in the smoke box behind the faceplate, one for up and down movement and one for left and right movement. This limited the range of movement of the eyes as well as being cumbersome and jamming often. Duke's side rods were sourced from a OO scale Triang Hall class with little modification. Duke's wheels were sourced from Slater's 10 Spoke Wantage Tramway driving wheels and 10 Spoke LNER 02 Bogie Wheels for the tender. These wheels were used on an O gauge locomotive chassis.
In the fifth season, Duke's model was painted a dark brown and given Smudger's facemask to create Bertram due to financial difficulties. Bertram's model was later reverted back to Duke, however, a 2004 promotional image revealed his model was incorrectly painted a lighter shade of brown and his buffer beam was not painted red. This error also transitioned onto TrackMaster and Wooden Railway toys.
Duke's grinning face-mask is now owned by Twitter user ThomasTankMerch.
Large Scale model
For ease of filming, Season 5 introduce larger-scale versions of the narrow gauge engines, and from Season 6-12 these larger models were used almost exclusively. They were built to a larger scale than the gauge 1 engines and ran on O gauge track. They were close to 16mm scale, but slightly larger. Due to budgeted reasons, no large scale model of Duke was built, which is why Duke never appeared after the fourth season (excluding portraits and stock footage cameos).
A large scale model of Duke was required for scenes in Sleeping Beauty and Bulldog where he had to interact with close-up scale figures. Two faces were sculpted for Duke. The close up Duke happy face was also used on the close up Peter Sam in this shot from Special Funnel.
As dressing for the large scale set, a portrait of Duke was made. The portrait was illustrated by art director, Robert Gauld-Galliers, and was roughly 80 millimeters in length and 60 millimeters in width. The portrait first appeared in the fourth season episode, Sleeping Beauty.
- Masaharu Satō (Japan)