Mr. Percival is Peter "Samuel" Percival's Son and Ivo Hugh' (The Person)'s Nephew
- Season 2 - 4 Little Engines! and Rheneas Comes Home
- Season 3 - Duke's Return, Rusty and Harold (mentioned), Duncan (episode) and Oh Peter Sam!
- Season 4 - Duncan and The Yellow Rheneas (mentioned)
- Season 5 - Murdoch, Salty and Harvey! (cameo), Fergus the Brave (cameo) and Rheneas' Snow Rescue!
He is likely to appear in the upcoming special, Wilbert the Forest Engine.
- In some scenes, Mr Percival uses Sir Topham Hatt's model.