Spencer is very arrogant and pompous and considers himself to be above doing menial duties such as shunting. None of the engines like him, especially Thomas and Gordon. When he came to build the summer house, Spencer proved himself to be very nosey, sneaky, disobedient and rather neglectful. Despite being closely related, Gordon and Spencer have never gotten on very well with each other. This is mainly because of his pompous behaviour, which exceeds even that of Gordon's. Despite this, he has shown a kind side when he realised his mistakes. This side once came through when he helped Percy find his way home to Tidmouth Sheds.
Spencer is an LNER Class A4 Pacific. Mallard, holder of the world speed record for steam locomotives, is another member of this class. An additional five members of this class survive in preservation.
Spencer was painted blue-grey with black lining. From the tenth season onwards, he is painted metallic silver, still with black lining. He has red nameplates with his name in gold.
- 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)
- 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; until nineteenth season)
- Paul Disbergen (The Netherlands; nineteenth season onwards)
- Gadi Levy (Israel)
- Dor Srugo (Israel; King of the Railway only)
- Torbjørn Hummel (Denmark)
- Ángel Amorós (Spain)
- Taisto Oksanen (Finland; Hero of the Rails onwards)
- Denis Bespalyy (Russia; King of the Railway - eighteenth season)
- Anton Savenkov (Russia; nineteenth season onwards)
- On the Steamies vs. Diesels DVD, Spencer is mistakingly called a diesel, even though he's a steamie. This is because in the game, Spencer says he does not have a whistle, but an electric horn instead. However, his picture clearly shows him having a whistle.
- One of Spencer's models used to be on display in Canada at Nitrogen Studios.
- Spencer's television series model was based on an A4 Pacific, but was slightly modified. The 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.
- Spencer's whistle is a stock sound effect of a GWR whistle.
- In late 2013, Spencer's Take-n-Play model was referenced in the BBC television programme "Have I Got News For You" being described as "A train that looks like David Cameron".
- Spencer's Hornby model incorrectly features him with black wheels. All other merchandise models have him with correct silver wheels.
- In his The Great Race promotional video, it states he is the holder of the world speed record for steam locomotives. In the actual special, it's stated that he's a former world record holder.
- Spencer is the first steam engine to be the main antagonist in a special.
- Spencer has been through several changes through the series. These include:
- Season 8:
- Spencer's bronze buffers changed to silver ones.
- Season 10:
- His blue-grey livery changed to metallic silver.
- Season 19:
- He gained two LNER headlamps and a tail lamp.
- Season 20:
- His livery became much more reflective.
- His whistle is now silver.
- Season 8: