The policemen are people who are a part of the police force. They patrol different locations on Sodor.
Once, a policeman came to argue with the Fat Controller after Thomas was found to have travelled down the Quarry Tramroad illegally, without cow-catchers and side-plates. Another time, Madge once sprayed one with snow and he was later present at the Narrow Gauge Engine Rally.
In Sodor's Legend of the Lost Treasure, the policemen arrested Sailor John for attempting to steal the treasure. There was also a policeman present during the rescue of a whale at Bluff's Cove. In The Great Race, a policeman can be seen dancing during the Thomas' dream sequence song, Streamlining.
In the twentieth season, one was on hand after Thomas derailed after crashing into a pile of debris that Max and Monty dumped over a bridge on his branch line. He subsequently berated them and ordered them to get it to the dump by morning.
- In the book based on Sodor's Legend of the Lost Treasure, it is revealed that the policemen also have patrol cars with red siren lights along with their bicycles.