After arriving at Tidmouth with the express, Gordon shunts a coach, named Sophia from the train into a siding for passengers wanting to travel to destinations on Thomas' Branch Line. Thomas, Annie, and Clarabel then come from Knapford Junction to collect her.
One time, Douglas accidentally forgot to shunt this coach for Thomas. Instead he shunted the coach, full of passengers, into the carriage siding causing a heap of confusion and delay for the passengers.
In the tenth season, Thomas didn't really think about treating Sophia the same way as Annie and Clarabel. But after a little accident, she now works regularly with Thomas, Annie and Clarabel instead of being based mostly on the Mainline.
Sophia is based on a British Railways Mark 1 Coach.
Sophia is painted burgundy red with cream coloured window surrounds.