Timothy is an oil burning tank engine that works at the Sodor China Clay Company.
Timothy loves to work at the China Clay Pits with Bill and Ben, but his naïvety can sometimes lead to the twins playing tricks on him. Despite this, Timothy just dismisses them as silly and gets on with his job.
Bill and Ben tricked Thomas into taking a train of trucks, unaware that Timothy was on the other end which Timothy claimed was a bit of a funny trick. He gave Thomas some advice about the dangerous crumbling clay pit walls and he also told him not to mind Bill and Ben's tricks so much. Thomas accepted Timothy's advice to be cautious.
Bill and Ben once teased Timothy for being an oil-burning engine instead of a regular coal-burning engine. Timothy started to get upset by this, but ended up having the last laugh when the clay pits ran out of coal. Timothy collected some coal from Brendam Docks and the twins finally apologised for their teasing. Sometime later, the twins sent him on a wild goose chase to Brendam Docks to find them a multi-coloured truck which they claimed that they wanted for doing something important which was one of their usual tricks, causing Timothy to run around the island until he came across a waste truck covered in red, orange, yellow, green, blue, indigo and violet paint. Salty claimed it to be a "rainbow truck". Timothy took the truck back to the China Clay Pits where Bill and Ben could smell the rubbish inside the truck. Sir Topham Hatt scolded Bill and Ben for their silly trick they played on Timothy and were told to take the truck to Whiff's Waste Dump as a punishment, so the China Clay Twins took the multi-coloured truck to the Waste Dump and got into an argument on the way which caused the China Clay Twins to call each other a stinky tank engine because the truck was smelly.
One time, Bill and Ben constantly said Timothy was "no help at all" whenever they made mistakes, though no one was fooled. However, they convinced the Fat Controller to send Timothy to Brendam Docks to help Porter, who was working on his own due to Salty working on The Mainland. But without Timothy, the work at the clay pits piled up. Finally Timothy came back with Salty and Porter behind him to help clear up the mess.