Since we know Gustavo, Kenji and even (the fictionalized) Iron Duke (thanks to Custom TrackMasters), here's context on "Earnest":
In the show's first season, a "Victorian style" portrait of a broad gauge engine with a moustache was created to look like the human portrait props in various sets and used on the Topham Hall (the Hatt family's mansion) set. It can be seen in the episodes "Thomas in Trouble" and "Thomas Comes to Breakfast" (Season 2; in the Ffarquhar Stationmaster's house). He had no name during production, so Robert Gauld-Galliers (who painted it) suggested "Earnest".
In the show's first season, a "Victorian style" portrait of a broad gauge engine with a moustache was created to look like the human portrait props in various sets and used on the Topham Hall (the Hatt family's mansion) set. It can be seen in the episodes "Thomas in Trouble" and "Thomas Comes to Breakfast" (Season 2; in the Ffarquhar Stationmaster's house). He had no name during production, so Robert Gauld-Galliers (who painted it) suggested "Earnest".