Copycat! is a magazine story.
One day, Percy was sent to pull trucks of sand. Thomas had already started, so Percy watched to see how many trucks he should pull. Thomas was annoyed that Percy was pulling the same number of trucks. He thought Percy was trying to copy him, so the cheeky tank engine calls Percy a "copycat". Percy laughed; he liked the idea of being a copycat.
A little later, Thomas went to take on water and Percy followed close behind. Every time Thomas spoke, Percy mimicked him - just like a parrot. This annoyed Thomas and he steamed off. Percy copied Thomas all day.
Later the two engines took exactly the same number of trucks to Knapford, where the Fat Controller was waiting for Thomas. He needs Thomas to take a big train of gravel to the harbour. Thomas says that he will do it right away and Percy, without even thinking, mimics Thomas. This gives Thomas an idea for revenge. He says to the Fat Controller, "oh, please, Sir, send me" and again Percy immediately copies him. The Fat Controller is pleased to have two such eager engines and tells them that they can share the train. Thomas found it funny that Percy had to share his extra duties and Percy felt so foolish, he did not say a word.
- Knapford does not look like its television series counterpart.