Bio:
Percy was most likely built by Avonside around 1905 and had gone through a subsequent rebuild in the years preceding his second-hand sale to the North Western Railway. He is said to have been found wearing Hunslet parts, according to workers at Crovan's Gate.
Percy was still a cheeky engine and often liked to play jokes on Gordon and James, but one day the other engines got their revenge when Percy failed to recognise 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, although Percy still received a reprimand from the Fat Controller for it


Persona
Writing in The Thomas the Tank Engine Man, Brian Sibley described Percy as "one of the most engaging engines in the shed, with his slightly roly-poly appearance and a look of wide-eyed innocence". As the television series has progressed, Percy has been dumbed-down in order to teach viewers difficult words: he would say "dingy-fried" where anyone else would say "dignified". He is also shown to make silly mistakes, but then fix them upon realising what he has done before further damage is caused.

Percy is incredibly accident-prone and holds the dubious record of the most accidents in one season - five!