Sir Topham Hatt has an office where he usually works when he is not busy talking to the engines or planning events. This is also where he receives messages from the stationmaster and other people about his engines whenever they are in trouble or need to talk to him.
In the Railway Series the main office was located at Vicarstown until 1925, when it was moved to Tidmouth following the agreement with the LMS allowing trains to run to Barrow-in-Furness. In the television series, the main office is located at Knapford, however others have been seen at Rheneas and the Sodor Search and Rescue Centre.
In the nineteenth series, the office was being redecorated, though Percy accidentally thought this meant Sir Topham Hatt was leaving the railway. Soon after, Sailor John blew up the office with a stick of dynamite so that he could steal the treasure being kept in the safe.
- Sir Topham Hatt's Office has had numerous modifications throughout the years:
- Series 2:
- A picture of an LMS 4-6-0 was added.
- Series 3:
- The office changed slightly, as a large window was added behind the Fat Controller's desk and there was more furniture, the picture of the LMS locomotive seen in the office in the second series was also removed.
- Series 4:
- The back window disappeared and the walls became wooden brown, the desk became smaller and the floor was made of cotton. A portrait of Duke was also added.
- Series 5:
- The desk was re-positioned and more furniture was added. Also, the portrait of Duke was removed, but it would be seen in a signalbox.
- Thomas and the Magic Railroad:
- The desk became smaller, the bookshelf behind the desk became a normal shelf with books on the top of it and the walls became a darker brown and more furniture was added. Also, portraits of Thomas from Thomas, Percy and Old Slow Coach, Henry from Tender Engines, James from Time for Trouble and Lady Hatt from Sir Topham Hatt's Holiday were added.
- Series 6:
- The office changed back to its Series 5 appearance, with the exception of the walls that remain with their darker brown colour. Also, the portraits of Thomas, Henry, James and Lady Hatt were removed.
- Series 14:
- The office changed a lot, as the walls changed colour from brown to grey like in the second series, it gained different windows and less furniture, a portrait of James from James Goes Too Far was added, albeit with his face removed and a photo of Henry from Toby's Afternoon Off was added as the picture for the Fat Controller's Calendar with his face also removed.
- The Adventure Begins:
- A portrait of a Climax Class C logging locomotive resembling Ferdinand was added.
- Sodor's Legend of the Lost Treasure:
- Journey Beyond Sodor:
- A large map of Sodor was added to the worktable, which Sir Topham Hatt would use with model engines resembling that of wooden railway engines, similar to the war map used by Prime Minister Winston Churchill in WW2, as a means to monitor where the engines are located on the island.
- Series 2:
- Plarail (discontinued)