- “You don't know the rules!”
- ―Fergus to Diesel
Fergus Breaks the Rules, retitled Thomas and the Search for Fergus in some American releases, is the eighteenth episode of seventh season.
The Fat Controller has brought Diesel to help out at the Cement Works for a while. However, Diesel becomes annoyed with Fergus. Later on, Diesel lies to Fergus about the Fat Controller sending him to work at the scrapyards. When Fergus arrives, 'Arry and Bert frighten the traction engine and he runs away. The Fat Controller receives a call that Fergus is missing. So, he sends Thomas to search for him. He finds Fergus hiding in a siding and takes him to the smelters yards where the Fat Controller is waiting. In the end, Fergus goes back to work at the Cement Works, and Diesel is transferred to the smelters yards.
- Sir Topham Hatt
- 'Arry and Bert (not named)
- Percy (cameo)
- Farmer Trotter (cameo)
- The Butler (cameo)
- Sodor Cement Works
- Sodor Ironworks
- Topham Hall
- Castle Loch
- Castle Loch Causeway
- Maithwaite Quarry Mine
- Going by production order, this is the nineteenth episode of the seventh season.
- Some scrap models of Thomas, Gordon, James, Donald or Douglas, Toad and City of Truro are seen in the smelter's as well as two of Henry's scrapped tenders from the third season episode Tender Engines.
- Stock footage from Bill, Ben and Fergus is used.
- This episode marks Fergus' last appearance to date.
- This is one of several episodes from the seventh season to have its title card read on Nick Jr. and PBS airings.
- Michael Brandon's American narration was used for the Hit Favourites DVD, The Groovy Collection.
- This episode marks the only appearances of Diesel and the Butler in the seventh season, as well as Diesel's last appearance in the Classic Series and the Butler's last appearance in the television series.
- Diesel says "Don't interfere!" after Fergus scolded him, but the closed captioning in the US home video release has him saying "Darn it to fear!"
- When Thomas and Fergus arrive at the smelters, Thomas' eyes are wonky.
- Just before 'Arry and Bert come into view, a crew member's hand can be seen holding them back and then releasing them.
- A red wire can be seen underneath Fergus when he first arrived at the smelter's yard.
- When Fergus arrives at the Smelters and escapes, his lamp is on his right side. When he hides in the siding, his lamp is on his left side.
- During some scenes at the quarry, Fergus' right front buffer is crooked.