Thomas the Tank Engine is the second book of The Railway Series published in 1946. This marks the first appearance of the titular blue tank engine, who would become such a popular character the whole series would eventually centre around him. The book was illustrated by Reginald Payne, who was the one to model Thomas on an LB&SCR E2 locomotive. However, he remains uncredited to this day. The book contains the following stories:
- Thomas and Gordon: Thomas the station pilot plays tricks on Gordon, who becomes furious and decides to get back at him. Next day, Thomas is late and forgets to get uncoupled after shunting Gordon's coaches. Gordon takes Thomas on a wild high-speed journey across Sodor. Thomas learns a lesson to never tease Gordon again.
- Thomas' Train: Henry is ill and Thomas is the only one available to take the Express. Unfortunately, he's so impatient that he leaves too early and only stops when a signalman points out he is missing his coaches. Thomas returns to the station and takes the train that time. He is teased by the others for a long time afterwards.
- Thomas and the Trucks: Thomas complains that he wants to see the world, but no one takes notice until Edward offers to give him his trucks. Thomas is excited but is careless, and the trucks push him down Gordon's Hill. Thomas manages to stop in time, and the Fat Director advises him to start shunting trucks at Wellsworth in order to be a Really Useful Engine.
- Thomas and the Breakdown Train: Thomas is shunting when some trucks push James into a field. Thomas comes to his rescue with the Breakdown Train, and is rewarded with two coaches and his own branch line.
The book contains examples of:
- All of the Other Reindeer: The other engines (minus Edward) towards Thomas.
- Attention Whore: Thomas.
- Bratty Half-Pint: Thomas who is described as "cheeky" and "fussy".
- Bully Hunter: Thomas didn't take it well when the trucks pushed James, causing him to crash in the field. He made them whimper in fear while he was clearing the accident.
- Earn Your Happy Ending: After rescuing James with the Breakdown Train, Thomas is rewarded with two coaches and his own branch line.
- First Day from Hell: James is pushed down Gordon's Hill by the trucks, the friction caused by the driver's attempt to stop sets his wooden brake blocks on fire, and he ends up crashing into a pasture.
- I Just Want to Be Special: What Thomas desires in the third book."I'm tired of pushing coaches! I want to see the world!"
- Jerkasses: The trucks in "Thomas and the Trucks" as the narration describes them as such.
- Jerkass Realization: The passengers are infuriated by Thomas' mistake, until he comes back looking extremely sorrowful and they feel sorry for him.
- Karmic Trickster: Gordon to Thomas.
- The Prankster: Thomas, but Gordon soon taught him a lesson.
- Runaway Train: The trucks push Thomas down Gordon's Hill, sending him rushing far past the station into a siding.