Montague was built in March 31, 1929, and worked at London's Paddington Station. He was nicknamed "Duck" by the other engines including the big engines because apparently he waddles like a duck. At first, he didn't like it because it was an insult from the big engines who love to order little engines about, but since he didn't like his real name, he finally grew bond with the nickname and allowed other engines to call him "Duck". He came to Sodor in 1955 to replace Percy's job of moving heavy goods about the yard, while Percy helped build Elsbridge Harbour. Gordon, Henry, and James found his ways of working very interesting, and decided to poke fun at it. They made fun of his nickname, and ordered him about. However, being proud of his Great Western Heritage, Duck stood no nonsense, and he and Percy barred them from the Turntable, claiming they couldn't let them through because they only took orders from the Fat Controller. The engines never ordered him about again. Duck managed easily with the goods work, but often annoyed the other engines with his "Great Western Way" talk. When Diesel arrived in June 1957, Duck tricked him into making a fool out of himself with Diesel's arrogance. Enraged, Diesel told lies about Duck, which the other engines believed so they turned on him. Duck was sent to Wellsworth while the Fat Controller sorted the whole ordeal out. After crashing into a barber shop, Duck came back, and Diesel had been sent away in disgrace while the others apologized. Because of his hard work, Duck was given the Arlesbourgh Branchline to himself in 1967.
SI3D's 2012 model of Duck is used. Previously, SI3D's 2010 model was used until The Great Railway Heist.
Duck is a GWR 5700 0-6-0PT pannier tank engine. He comes with two sandboxes just in front of his tanks, although one of the RWS Trainz models doesn't depict it, like in The Way of the GWR.
Duck is hard working and extremely diligent. He takes no nonsense from anyone. He is also extremely proud of his Great Western heritage, and loves to do things in the proper way, which can annoy the other engines. Duck has never been truly naughty, although he did play a trick on Diesel to teach him a lesson.
- A Wretched Day for Henry and James
- Gordon Goes Swimming
- Bill and Ben the Brave Brothers of Brendam (cameo)
- Mike Takes the Road
- Engine Unknown (mentioned)
- A Tale of a Small Green Engine (cameo)
- The Runaway Railcar (cameo)
- The Devious Diesel (does not speak)
- Sent Packing
- Oliver's Tiny Tale
- The Sodor Garratt (cameo)
- Duke's Reunion (cameo)
- Revolutionary Redemption (mentioned)
- The Great Railway Heist (cameo)
- Diesels and Dragons (cameo)
- Painful Memories (appears in flashback, cameo)
- Haunted Henry (part 2 only)
- How the Diesel Stole Christmas
- The Search for Smudger (part 2 and 3 only)
- The Most Famous Engine
- Tarnished Legacy
- Tank Engine Mixup (cameo)
- Smuggling from Scotland
- Great Western End (appears in flashback, does not speak)
- Great Western Escape
- MallardFan62: Episode I-XI
- Thomas1Edward2Henry3: The Search for Smudger-onwards
- Waltsland: The Most Famous Engine-Other Specials + NWR Origins
Duck was introduced in the second season episode Duck Takes Charge. He appeared regularly in every season since until Season 8, which then he was completly absent until Season 12. He was then absent again until Season 17. He then appeared in every season since. He is voiced by Steven Kynman in the US and UK, being the first member of the NWR 11 to have the same voice for both dubs.
- Duck was the first steam engine to speak in The Engines of Sodor.
- Duck is one of the most popular characters of the fandom. T1E2H3 believes it's just because of the long absence of a main character.
- Duck is the only member of the NWR 11 not to have a RWS book with only his name in the title (ex. Thomas the Tank Engine). The book dedicated to him was called Duck and the Diesel Engine. This does not count the The Twin Engines, who are twins and should have the same book.
- Duck originally did not have an Origins episode. Along side Toby and Percy, because T1E2H3 thought it would just be remakes of when they arrived. However,he had one in NWR Origins' Season 2.