Percy the Small Engine is the eleventh book of The Railway Series published in 1956. The four stories are:
- Percy and the Signal: After playing jokes on Gordon and James, Percy decides to stay out of their way for a while, but when he is asked to take a train to Knapford he gets careless and goes over to tell them. Seizing their chance, they warn him about "backing signals", and as he stops for the signal outside Knapford, he is convinced that he is waiting for a "backing signal". He ends up making a fool of himself, and Gordon sees the whole episode.
- Duck Takes Charge: The Fat Controller is getting a new engine to help Percy, but Gordon and James tell Percy that if he worked harder they wouldn't need one. Percy, cross, works all day and is exhausted, but is happy when the new engine, Montague, known as Duck for his "waddle", arrives. They have a happy day together, but then the big engines order them about. Percy and Duck, in retaliation, block the entrance to the sheds. The Fat Controller comes and tells all five engines off. Percy is sent to work at Knapford, and Duck manages the workload alone.
- Percy and Harold: One day at the airfield Percy meets a noisy helicopter, Harold, who says railways are slow and out-of-date. Percy, furious, is later taking some trucks to Knapford when he sees Harold in the air and decides to race him. At the harbour, Percy thinks he's lost, but his fireman sees Harold looking for a place to land. In congratulation, his crew and the workmen sing a song about the race.
- Percy's Promise: Thomas is busy and asks Percy to take the Sunday School children home. Percy agrees, but it starts to rain heavily as it's time to leave. Percy stops in front of a flooded paddock, but can't go back, as a bridge has collapsed. As he crosses the paddock, water sloshes into his fire and he stops. Percy struggles on, fueled by floorboards from the guard's van. After Harold drops some supplies for them, unfortunately landing on Percy's boiler, they make it to safety, and the Fat Controller congratulates the two.
The book contains examples of:
- The Big Race: "Percy and Harold".
- Bratty Half-Pint: Percy to the big engines.
- Bullying a Dragon: As the narration puts it, the trucks found out that playing tricks on Duck was a mistake.
- Bully Hunter: Duck and Percy stood up against Gordon, James, and Henry.
- Determinator: Percy in "Percy's Promise".
- Fantastic Racism: Harold states that railways are slow and out of date.
- Gang of Bullies: Gordon, James, and Henry in "Duck Takes Charge".
- Jerk with a Heart of Gold: Harold in "Percy's Promise". Despite being snobbish about the railways in "Percy and Harold", he came to Percy's aid during the storm.
- Karmic Tricksters: Gordon and James to Percy in "Percy and the Signal".
- Only Known by Their Nickname: Duck's real name is Montague, but he prefers to be referred to as Duck.
- The Prankster: Percy.
- Racing the Train: In "Percy and Harold", this is a variant of Train vs Helicopter.
- "The Reason You Suck" Speech: James gives one to Percy after hearing him talk about the news about The Fat Controller bringing a new engine, Duck, to help with the yard work.James: Rubbish! Any engine could do it! If you worked more and chatted less, this yard would be a sweeter, better, and a happier place!
- Silence, You Fool!: The Fat Controller does this to Gordon, James, and Henry who were wheeshing.
- "The Villain Sucks" Song: Percy's fireman sings this song in celebration of Percy's victory against Harold:Said Harold Helicopter to our Percy, "you are slow
Your railway is out of date and not much use, you know"
But Percy with his stone trucks took the trip in record time
Annnnd! We beat the helicopter on our old branch line!
- What the Hell, Hero?: Despite commending them for their work, The Fat Controller reprimands Percy and Duck for blocking the turntable to the sheds to keep Gordon, Henry, and James from getting in and causing a disturbance. The bigger engines are laughing about this until The Fat Controller rounds on them and snaps at them that they were worse as they had made the disturbance.