Niles is a grey maintenance diesel who is the number 9 on the Culdee Fell Mountain Railway. He was the first diesel on the line, and is often nicknamed "The Mouse" because of of his small appearance. Niles is a fan character.
Niles was built in 1997, 11 years after his Welsh counterpart, at Crovan's Gate. He was the first Culdee Fell Railway engine to be built there. After competing his tests, he arrived at Kirk Machan in March. His first job was to double head (or rather, double-tail) a passenger train with Patrick. Patrick was not very keen on sharing his train because of his prejudice, and he was very churlish with Niles. While on the last ascent, they got stuck behind Culdee who had broken down. Niles, being built for strength, pushed Patrick, Culdee, and both their coaches up to the summit and back down to Kirk Machan. Both were amazed, and Patrick later apologized for his rude attitude. The two are now friends.
Niles is supposed to be based on Ninian from the Snowdon Mountain Railway. However, because a model of this couldn't be found, the 36in Shunter Body from Trainz is used because it looks the most similar. Rusty's face was photo-edited in after filming.
Niles is very optimistic and friendly. He is always eager to work.
- When creating the character, T1E2H3 used traditions of the Rev. Wilbert Awdry, such as naming him a similar name to his counterpart (eg. Ernest is based off of Enid).
- Niles has an Australian accent. T1E2H3 just thought it would be cool if he had one. All the Culdee Fell Engines will have a distinct accent.
- Niles is the first fan-made engine introduced in T1E2H3's Railway Series.