The Twin Engines is the fifteenth book of The Railway Series published in 1960. This contains four books:
- "Hullo Twins!": The engines are getting dragged down by the amount of work they have, and they are pleased to hear a goods engine is arriving from Scotland. However, the Fat Controller is surprised to hear that two engines have arrived and goes to meet the engines, but only manages to discover they have "lost their numbers", as they put it, and they have since named themselves Donald and Douglas. The Fat Controller orders for them to have numbers painted on them and puts them to work, but is determined to find out which engine should not be there and send him back.
- The Missing Coach: Donald and Douglas (now #9 and #10 respectively) realize they only have numbers painted on their tenders. One afternoon, Douglas is shunting in the Yard and worries about being sent away, unfortunately forgetting to shunt Thomas' Special Coach. The twins decide to swap tenders so as to convince the Fat Controller that Donald has taken his goods train, but he isn't fooled and reprimands Douglas severely.
- Break Van: The Fat Controller threatens to send one of the twins away and they behave, until a spiteful brakevan delays Douglas' goods train. Donald soon puts the van right, but when Donald crashes into a signalbox and James has to do his goods work, the brakevan and the trucks, sensing James' fury, hold back, and Douglas has to help as a "banker". The brakevan holds back again, but gets its comeuppance after Douglas accidentally crushes it. The Fat Controller comes to supervise the clean-up, and has mixed feelings about Douglas staying.
- The Deputation: Winter comes early, and Donald and Douglas ask to help clear the line. They manage to rescue Henry from a snowdrift, but they are still worried that they will be sent back. Edward tells Percy that they need a "deputation", and the big engines elect Percy to be their "disputation". Percy tells the Fat Controller that Donald and Douglas will be scrapped if they return to Scotland, but the Fat Controller has already made up his mind: he gives the twins a new coat of paint and allows them to stay.
The book contains examples of:
- Accidental Murder: Douglas accidentally kills the Spiteful Brake Van by crushing him to pieces.
- Armor-Piercing Question: "Douglas, why are you masquerading with Donald's tender?"
- Asshole Victim: The Spiteful Brakevan. James even mentions how glad he is that it is broken to pieces and never repaired.
- Beat:Henry: What is a desperation?
Percy: It's when engines tell The Fat Controller what's wrong.
Duck: Did you say "tell The Fat Controller"?
[beat]
Gordon: I propose that Percy be our...disputation. - Berserk Button:
- For Duck, calling the Great Western Railway "tinpot railway".
Duck: Tinpot indeed! Let me tell you!- For the twins, having their whistles being made fun of, as Gordon and Henry found out.
- For James, being reminded of crashing into the tar wagons.
- Big Brother Instinct: Twin-brother instinct, actually (though it's confirmed Donald is the older one, so it still counts). Donald was furious when the Spiteful Brake Van caused Douglas' trains to be late and gave him a big bump.
- Some of the dialogue also implies that Donald has helped to smuggle Douglas over to Sodor to save his life.
- Big "SHUT UP!": James says this to Gordon and Henry who laugh when Douglas reminds him of the tar accident.
- Bully Hunter: The twins stood no nonsense from the troublesome trucks and stood up to Gordon and Henry for making fun of their whistles. Donald was this when he gave the Spiteful Brakevan a hard bump on behalf of Douglas.
- Call-Back: Douglas' recall of James crashing into tar wagons in "Dirty Objects".
- Chronic Backstabbing Disorder: The trucks hold down James' train at the Spiteful Brakevan's command. When Douglas pushes again the brakevan, crushing him, he moans at the trucks to go forward. They're enjoying themselves too much to care, and keep holding back until Douglas ends up smashing the brakevan by mistake.
- Chronic Villainy: Even after one hard bump from Donald, the Spiteful Brake Van returns to his troublesome ways as he tells the trucks to hold James back.
- Does Not Know His Own Strength: Douglas pushes at James' train only to crush the brakevan by mistake.
- Don't Split Us Up: Donald and Douglas really didn't want to part from each other. This even provides the quote of the tropes page.
- Earn Your Happy Ending: Despite their troubles with the Special Coach, the signalbox, and the Brake Van, Donald and Douglas are here to stay in The Fat Controller's railway. Cue all of the engines whistling with joy.
- Felony Misdemeanor: Gordon and James respectively complained about how the twins were going to be sent away because Donald accidentally broken a signal box and Douglas smashed the Spiteful Brake Van into pieces.
- The Freelance Shame Squad: Gordon and Henry laugh about Douglas' remarks about James' accident with the tar wagons.
- Given Name Reveal: The official name of the Express, the "Wild Nor'Wester", is given for the first time.
- Got Volunteered: Percy in "The Deputation".
- Jerkass: The Spiteful Brake Van.
- Douglas is this when he reminds James of his accident with tar tankers.
- So are Henry and Gordon for sniggering.
- The troublesome trucks for holding James back.
- Karmic Death: The Brake Van was unintentionally broken by Douglas. This is fitting considering that he was the one that caused engines' trains to be late.
- Kick the Dog: Douglas making fun of James's incident with tar tankers.
- Mythology Gag: The Fat Controller's question "Now, which one of you is 57646?" is this; the 812 class, to which Donald and Douglas belonged, only went up to 57645 in their numbering sequence.
- Oh, Crap!: Percy after being volunteered to confront the Fat Controller. Also, he almost jumps when he comes before him.
- Parrot Expo What: The engines aren't sure what a "deputation" is.Percy: Edward says we need a depotstation.
Gordon: Of course. The question is...
Henry: What is a desperation?
Percy: [smugly] It's when engines tell the Fat Controller something's wrong, and ask him to put it right. - Remember the New Guy?: The coach transferred from the Express to Thomas' branch line is mentioned and shown for the first time. It’s never mentioned again.
- It Seemed Like a Good Idea at the Time: The Spiteful Brake Van soon starts to regret his prank when he's stuck between Douglas pushing him and the trucks holding the train back. He tries to get the trucks to call it off, but they couldn't care less, and the Brake Van is eventually crushed by accident by Douglas.Spiteful Brake Van: Oh-er! I wish I'd never thought of this!
- Skewed Priorities: The Signalman got annoyed with Donald for jamming his points, rather than endangering his life.
- Smug Snake: The Spiteful Brake Van as covered by this quote:Spiteful Brake Van: You can't. I'm essential.
- True Companions: In "The Deputation", all of the engines are quick to defend the twins despite the trouble they caused previously.
- Twin Switch: Donald and Douglas do this after the latter forgets to shunt Thomas' Special Coach, but they are soon found out by The Fat Controller.
- What the Hell, Hero?: Donald and Douglas receive some severe reprimands from the Fat Controller.
- First, he scolds the twins for swapping their tenders to avoid Douglas being founded out for misplacing Thomas' special coach and then tells them he’ll find out which twin will be sent back.
- Along with the signalman, the Fat Controller tells off Donald for smashing the signalbox, ruining his arrangements in sending Douglas back and leading him to assign James with extra work.
- He later roasted Douglas after he destroyed the Spiteful Brake Van, and has no idea which engine to send away.
- Whole Episode Flashback: The events of this book takes place in 1959.
