- "Two tricks in one day... that's a bit excessive isn't it big guy?"
"Honestly for you two that's cutting back!"
- ―Bill and Ben talking to BoCo
Bill and Ben are two mischievous twins that work at the China Clay Works and on Edward's Branch Line.
Bill and Ben arrived on Sodor in 1965 to work at the China Clay Works. At first, The Fat Controller sent them to work at the Harbor collecting trucks and taking them to the China Clay Works. One particular day when they were new on Sodor, they discovered that their freight cars had gone missing, and there was a patch of oil in the place of where the train should have been. Confused and angry, the twins deemed the thief a "Diseasel" and came up with a plan to get their trucks back! The "diseasel" turned out to be BoCo and after they made up their mistake, Edward took away the naughty twins, for it is said that he is the only one who can handle him!
Bill and Ben jokingly threatened to launch Gordon into the sea when the big blue engine accidentally ended up at the harbour after a train schedule mix-up, for that's what they were told to do with "scrap iron"! Luckily for Gordon, BoCo came and stopped the twins' nonsense.
Bill and Ben wanted to be heroes, and proved their worth when they saved workmen from a rockslide in the quarry.
When Fergus kept nagging the twins to "do it right" whenever they did anything wrong, they got fed up and decided to disobey Fergus by taking some heavy machinery past a dangerous rock face. This caused a rockslide and the twins would have been crushed had Fergus not pushed them out of the way in the nick of time and been buried in the rocks himself. Bill and Ben helped dig him out of the rocks and resolved never to be cheeky to Fergus again.
Bill and Ben enjoy teasing the bigger engines while they work at Brendam, much to the displeasure of Murdoch. However, when Murdoch expertly orchestrated a prank against Gordon, he certainly won the twins' respect!
They occasionally work at the Blasting Site without BoCo to keep them in line, which makes them even more naughty! That naughtiness has surfaced numerous times recently, including an accident in which the Flying Scotsman was late for a meeting at Tidmouth Sheds and had to be dug out by Diesel 10, Thumper, and Sidney.
After a rockslide occurred in the Clay Pits and blocked a line, the Twins tricked Derek and the diesel ended up colliding right into the rocks on the line. When Billy arrrived to work in Derek's place, the Twins continued to be cheeky until Edward stopped them, then resumed their usual ways when Marion needed a chance to prove herself!
Their pranks finally came to a head however, when they tricked Donald to go onto a siding with unsafe buffers, saying that they had been repaired and that Donald's trucks were there. They did not take into account however that the unsafe buffers were at the edge of a cliff, and Donald ended up going off the cliff and was badly damaged. After this accident, Edward rushed the twins to Crock's Scrap Yard in order to both punish them, and keep them safe from Douglas potentially attacking them! The two apologized, truly horrified at what had happened, but Douglas stated that it would take a while for him to forgive them. Afterwards, Edward looked over the twin's past tricks, and from that point onward, had Marion act as their chaperone so as to prevent accidents like Donald's in the future.
Bill and Ben are the most mischievous little engines on the North Western Railway. They are cheeky, naughty, and love to play tricks on the other engines- even if they get into trouble. Despite this however, they work hard and help out as best they can and know that if things don't go the way they plan, they can always learn from them and try as best they can to make things better next time.
- Season 1: Lift Bridge (Ben only, cameo), Life Boats (cameo), Shepherd's Pie (Ben only, cameo), Buffer Bashing (one speaks, other cameo), Cannon Fodder (cameo), Conspiracy Theory (Ben only, cameo)
- Season 2: Scot-free, Mavis and the Tornado (cameo), Rosie (cameo), Rock-Star, Munitions (cameo), Swan Dive, Swashbuckler (cameo), Self-Fulfilling Prophecy (cameo, possible speaking role)
- Season 3: Marion Saves the Day, This Too Shall Pass, Perhaps He's Got a Corset (mentioned), Derek and the Two Faced Engines (flashback; do not speak)
- Web Clips: Mike and Frank Banter: SLOTLT, ScarletFire, and EE93's Return (Bill or Ben cameo), Gina gives Percy some pointers - Meet the Characters! (cameo), Timothy, Bill, Ben, and Marion - Meet the Characters!