Thomas was the station pilot at Vicarstown for eight years until he rescued James from a terrible accident. Since then, The Fat Controller has given him a branch line of his very own, where he now works happily with Toby, Percy, Mavis and Daisy (until the latter soon went to work on the Harwick Branch Line) and his faithful coaches, Annie and Clarabel.
Thomas is a rather cheeky, but good hearted and kind engine and generally behaves well, except when he is getting into mishap from getting over-eager. He loves teasing the others, especially the bigger engines, such as Gordon and on occasion, brags about his superiority, but is always brought down to earth in due course by anyone who gives him the moral to learn, especially the Fat Controller, and his two coaches, Annie and Clarabel. If Thomas has one major character flaw, it is that he is forgetful and slightly impatient. However, he is also optimistic and idealistic.
Although their friendship has been turbulent at times, Percy is Thomas' best friend.
Thomas is youthful, playful and also loves making children smile and he'd do anything to make somebody's day a better one. Annie and Clarabel are his closest friends of all.
Thomas is painted in the North Western Railway's standard blue livery with red-and-yellow lining and the number "1" painted on his tank sides in yellow with a red border.
When Thomas first arrived on Sodor, he was painted teal-green with white-and-yellow lining. He had LBSC lettering painted on his tanks in yellow with a red border and had the number "70" painted in the same colours on the sides of his bunker. Upon his first visit to the Steamworks for a repaint, his metal frame devoid of paint is seen before being applied with a pink undercoat to keep water out from him, which would cause permanent rust damage.
- Season 1 - Geoffrey's Real, Percy's Oil Spill, Edward Tries His Best, Skarloey Comes Home (cameo), Salty's Secret Story, Gordon, Spencer and the Flying Scotsman, and Tinsel on the Tracks
- Season 2 - Disappearing Diesel, Haunted Henry's Forest (cameo), Fire at Ffarquhar, The New Controller, Jealous James, The Return of Boulder (mentioned), Jack and the Quack, Back to Misty Island, Sodor Day, Pile Driver Pedro, and Ministry (flashback cameo)
- Thomas was the first character introduced in the television series, unlike the Railway Series. Though in The Adventures on Sodor, the first character(s) seen onscreen in the first episode were the dockside team.
- Thomas' LB&SCR number (No. 70) actually belonged to an LB&SCR A1 named Poplar, a member of Stepney's and Boxhill's class. The engine containing this number is currently preserved at the Kent & East Sussex Railway. The number 70 also represents the 70th anniversary of the Thomas & Friends franchise.
|North Western Railway|
|Thomas • Edward • Henry • Gordon • James • Percy • Toby • Duck • Donald and Douglas • Oliver • Bill and Ben • Daisy • BoCo • Bear • Neil • Harvey • Emily • Fergus • Arthur • Murdoch • Molly • Neville • Rosie • Whiff • Stanley • Hank • Flora • Victor • Charlie • Bash and Dash • Ferdinand • Scruff • Belle • Porter • Timothy • Marion • Logan • Glynn • Ryan • Geoffrey • Diesel • Mavis • Derek • Diesel 10 • 'Arry and Bert • Salty • Dennis • Den • Dart • Sidney • Paxton • Norman • Philip • Flynn • Winston • Stafford • Dustin|