Stepney's Branch Line runs from north of Crovan's Gate to Great Waterton. Due to a vast amount of Bluebell flowers beside the tracks, the line is nicknamed "Bluebell Railway".
Stepney and possibly Flora currently are the only locomotives to work on this line, however Thomas has been seen travelling up and down it numerous times and other North Western Railway engines sometimes use this line to get to Great Waterton instead of using the Main Line.
The line begins northeast of Crovan's Gate, at the Transfer Yards on the Norramby Branch Line and travels up to The Depot and Mr. Percival's House, where it runs next to the Skarloey Railway until it splits at Bluebell Valley Station.
- The branch line is loosely based on the Bluebell Railway.