Spencer/Behind the Scenes

Gauge 1 model
Spencer's model was scratch-built to run on gauge 1 track. Spencer and his tender were cast from molds, he was one of the very few engines during this era to be made from a fiberglass resin. Spencer's body ending up being widened by model-maker, Ray Lovell. His axles were accommodate the non-scale sideways shift to cope with tight curves.

Eight different facial expressions were worn by Spencer on screen. The faces were first sculpted in clay, and from that resin casts were made using a silicone mold. Two faces were sculpted by model-maker, Jeremy King.

The model was track powered, so pickup contacts were attached to the metal wheels, which ran into the motor to power it. The electricity ran from the track to the wheels/pickup contacts and went into the motor to power him. Spencer's chassis were built by model-maker, Steve Knowles.

The eye mechanism had two servos, one for up and down movement and one for left and right movement. The up/down servo was attached to the body. The left/right servo had a rod attached to the arm, which connected to a bracket. The eye balls were coupled to the bracket, and locked in by the face-plate, so whenever the servos were powered, the eye balls would move however the crew member desired.

Unlike his basis, Spencer's smoke box was much less angled than it should have been due to the eye mechanism inside. This trait was carried on into the CGI switchover. In addition, Spencer has been through several changes through the series. In the eight season, Spencer's bronze buffers were changed to silver ones. In the tenth season, his blue-grey livery changed to metallic silver.

Spencer could often be seen with miniature scaled figures inside his cabs, these figures represented his drivers. One of Spencer's models used to be on display in Canada at Nitrogen Studios.

Close-up model
Several close-up shots of Spencer's cab was required for scenes in HiT Entertainment the show's long-standing live-action models. The following year, Spencer was recreated from scratch in CGI by Nitrogen Studios. His model was "hand-sculpted" in Maya, a 3D animation and modelling software.

Photographs of Spencer's Gauge 1 model were for referencing. According Greg Tiernan, every detail of the original TV models for each character is carefully reproduced in the CGI model. The models are subjected to many rounds of review before they are submitted to HiT Entertainment for final input and approval.

Spencer has had modifications throughout the CGI era. These include:
 * In a brief scene of King of the Railway, while crossing the Vicarstown Bridge, Spencer can be seen with black wheels and his name missing from nameplate.
 * In the nineteenth season, he gained two LNER headlamps and a tail lamp.
 * In the twentieth season, his livery became much more reflective.
 * In the twenty-first season, he received a detachable snowplough to the same design of Emily's.

Voice Actors

 * Kerry Shale (UK; Hero of the Rails; original cut only)
 * Matt Wilkinson (UK; Hero of the Rails onwards)
 * Glenn Wrage (US; Hero of the Rails onwards)
 * Yasuhiko Kawazu (Japan; seventh and eighth seasons)
 * Shigenori Sōya (Japan; tenth season onwards)
 * Till Huster (Germany; Hero of the Rails onwards)
 * Oliver Rohrbeck (Germany; Audio Books only)
 * Marek Robaczewski (Poland; Hero of the Rails onwards)
 * Paweł Galia (Poland; Creaky Cranky and O the Indignity only)
 * Espen Sandvik (Norway; Hero of the Rails - seventeenth season)
 * Tony Marot (France and French speaking Canada; eighth season onwards)
 * Leonardo García (Latin America; Hero of the Rails onwards)
 * Danny Houtkooper (The Netherlands; Hero of the Rails only)
 * Reinder van der Naalt (The Netherlands; thirteenth - eighteenth season)
 * Paul Disbergen (The Netherlands; nineteenth season onwards)
 * Gadi Levy (Israel; Hero of the Rails onwards, excluding King of the Railway)
 * Dor Srugo (Israel; King of the Railway only)
 * Torbjørn Hummel (Denmark)
 * Ángel Amorós (Spain)
 * Taisto Oksanen (Finland; Hero of the Rails - fifteenth season)
 * Juhani Rajalin (Finland; King of the Railway onwards)
 * Vladimir Antonik (Russia; thirteenth - sixteenth seasons)
 * Denis Bespalyy (Russia; King of the Railway - eighteenth season)
 * Anton Savenkov (Russia; nineteenth season onwards)