The Twin Engines is the fifteenth book of the Railway Series.
Sir Topham Hatt has just been having a disturbing time! He ordered one goods engine from Scotland and was surprised to receive two!
They had both lost their numbers and no one knew which was which. So he didn't know which engine to keep.
The engines, dragged down by the amount of work they have, are pleased to hear a goods engine is arriving from Scotland. However, two engines arrive, a surprised Sir Topham Hatt goes to meet the engine, attempting to sort the matter, 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.
Donald and Douglas (now #9 and #10 respectively), before setting off to being shown around the yard by Duck, realise they have only numbers painted on their tenders. After such, one afternoon, Douglas is shunting in the Yard and worries about being sent away, unfortunately forgetting to shunt Thomas' Special Coach. To evade the angry complaints of the passengers, the twins decide to swap tenders so as to convince the Fat Controller that Donald has taken his goods train, but to no avail, the Fat Controller, not being fooled, reprimands Douglas severely.
Under the threat of one of the twins being sent away, the twins behave fairly well, until a spiteful brake van causes trouble for Douglas. Donald soon puts the van right, until Donald crashes into a signalbox while backing into a siding. The Fat Controller, despite deciding to send Douglas back and keep him, scolds Donald, having upset his arrangements again; assigning his goods work to James in the meantime. With the brake van and the trucks sensing James' fury, they give him a hard time pulling his train. Eventually, Douglas has to help James up Gordon's Hill as a banker. The brake van holds back again, but gets its comeuppance after Douglas, while straining up the hill, accidentally crushes it. The Fat Controller comes to supervise the clean-up, and has mixed feelings about Douglas staying.
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. The engines, upset over the possibility of the twins being sent back, under Edward's advice to Percy, organize a deputation, assigning Percy as their representative. Percy pleads with the Fat Controller, telling them that Donald and Douglas will be scrapped if they return to Scotland, but the Fat Controller, already having made up his mind: gives the twins a new coat of paint and allows them to stay, met with thunderous whistles and cheers of joy between the engines.
- Donald and Douglas
- The Spiteful Brake Van
- The Fat Controller
- Annie and Clarabel (do not speak)
- The Foreign Gentlemen (do not speak)
- The Fat Controller's line "Now, which one of you is 57646?" is a subtle joke, as, in reality, the 812 class' numbers only went up to 57645.
- Gordon references Tugboat Annie, a 1950s Canadian television series about a tough old widow who captained a tugboat.
- A TV Series adaptation of "The Missing Coach" along with Break Van and The Deputation was planned for the second season, confirmed by David Mitton. However, Britt Allcroft scrapped the idea halfway through production, citing that the plot would be too complicated for young viewers. The twins swapping tenders is presumed to be the confusion of the plot. therefore the production crew had to make a whole new episode, "Thomas, Percy & The Coal" in order to stop the season being short of an episode.
- The illustration on the front cover shows one of the twins with British Railways' cycling lion logo.
- The title of "Break Van" is a play on the word brake van, as in the story, the van breaks.
- When Percy, Gordon, and Henry mix up the pronunciation of "deputation", Edward is visible in the shed; however, he does not correct them. Furthermore, it is mentioned that Percy ran back to the shed quickly, implying that he went immediately back. Edward was previously seen with some coaches, so if he had to take a train or shunt the coaches, then Percy should have arrived at the shed long before he did.
- In the fifth illustration of "Break Van" the Spiteful Brake Van is facing forwards, but in the next illustration, he is facing backwards. Also in this illustration, James' black lining, along his wheel arches are gone.