Toby was built by James Holden at GER's Stratford Works in Stratford, London, England in 1914 and originally lived at Great Yarmouth Docks, Norfolk with his brothers before working on an unnamed tramway. In 1951, Toby came to work at the quarry on Thomas' Branch Line after his old railway in East Anglia closed, as it was found to be illegal for Thomas to go on the quarry tramroad without sideplates or cowcatchers.
When he was first introduced, Toby was old but hardworking, and knew enough about running a branchline to justify running Thomas' with Thomas and Daisy after Percy's accident with the trucks. He is also savvy enough to control the trucks. However, his advanced age and design means that he is weaker than the other engines.
Since the eighth season, Toby has been portrayed as being nervous about the capabilities of his work and uncertain about being an old steam tram, believing that he is not a proper engine, only good enough as a museum piece and not really special at all.
Toby enjoys listening to the birds in the birdhouse next to his shed. He also is friends with the pigs at Farmer Trotter's Pig Farm.
In the Railway Series Toby was painted brown with black cowcatchers and sideplates (which sported "LNER" in bright yellow letters) before working on his tramway, where he was repainted greyish-brown with grey sideplates and cowcatchers. After helping James he was repainted chocolate-brown with olive frames and blue sideplates.
In the television series, Toby has consistently been painted brown with grey sideplates and cowcatchers. Toby has a number "7" painted on his sides in bright yellow with a red border.
In the Railway Series, he carries two plaques on the sides of his cab stating that he works on the NWR, his number, and the last time and place that he was rebuilt.