Percy ran Thomas's branch line while Thomas ran the Main Line with Edward and was allowed to stay after the big engines surrendered. At first, Percy liked to annoy the big engines. Percy was later waiting at Tidmouth but forgot to whistle to the signalman, and thus was startled when Gordon came rushing towards him with the express. Gordon managed to stop in time, but Percy was frightened, ran away, and ended up in a sandbank. He was rescued by Gordon and took up the duty of station pilot at Tidmouth.
Percy was still a cheeky engine and often liked to play jokes on Goordon and James, but one day the other engines got their revenge when Percy failed to regonise a "backing signal". After this, Percy was subject to bullying from the big engines until Duck arrived and helped Percy to put the big engines in their place.
With Duck's arrival, Percy was sent to Thomas' Branch Line to help build the harbor and has stayed there ever since as a goods engine.