Derek is the eleventh episode of season 1.
In 1981, a class seventeen diesel named Derek is bought to help on Edward's branchline. At the china clay quarry, Bill and Ben are acting up until BoCo and the quarry manager tell them to be quiet. The quarry manager explains that Sir Topham Hatt bought a new diesel to help them and the twins reply a smirk tone about their manager to BoCo. BoCo tells them to get back to work. Derek approaches Gordon's Hill during the rain and his engine is acting up in which once he arrives at the top, his engine breaks and is stuck. At Wellsworth, Edward is told to get Derek and to bring him back to Wellsworth. He does so and Geoff takes him to the works. An hour later, the sun comes out and Edward arrives at Brendam explaining both to Salty and Bill that Derek will not make it until tomorrow. Bill then returns to the quarry and tells Ben that Derek didn't make it. The quarry manager arrives and tells them that they need to drop off the last train to Knapford Harbour and to spend the night at Brendam. They tell Salty that they are tired from the day and he mentions that Derek will be arriving tomorrow. The next day, Derek comes to help the twins with the first train stating that he will take the back and they take the front adding what fun is that. They soon set off and hit a bad section of tracks on the drain which loosens a couple of bolts on Derek's newest engine. As they pass the orchard, Derek's engine acts up until they are a few feet from Wellsworth and that's when he breaks down. BoCo then takes Derek to the works while Bill and Ben continue on with the train. Later that night, Bill and Ben state that Derek was a friendly sort and are hoping that he returns back to service. BoCo states that he may be relocated to another part of Sodor. At the works on the same night, Chocolate mentions to Derek that Sir Topham Hatt decided to keep him and help on Edward's branchline. After he was fully repaired, he served the rest of his life on the line and helping out whenever he can including the old Suddery Port.
- This episode was aired before Complaints, Rusty and the Boulder, and A Change of Work as it was for a friend of Donald9andDouglas10 who had a birthday and it was top priority.
- Donald9andDouglas10 received lots of emails from many people including the tour manager of the band Journey that they enjoyed the episode. One of the emails was from his friend who said thank you and to always choose the right path.
- A fun challenge was created by Donald9andDouglas10 for the episode saying to find all three of the horrid lorries that make cameos in the background.
- A hidden message was in the episode that was taken from the original Thomas episode that this was adapted from. Some people who weren't familiar with the original episode, didn't even know there was a hidden message.
- This is the only appearance of TheSodorSteamworks as Bill, Ben, and Derek as their original voice actors had broken computers. TheSodorSteamworks will be taking over for Peter Sam after episode ten.
- Donald9andDouglas10 repeated the same line "The rain fell down" when Derek was both approaching Gordon's Hill and breaking down on the hill
- Bulgy appears to be driving backwards in one scene.