"... but Catherine's so clever, that I know at once if anything is wrong!"
— Culdee, Mountain Engine, Mountain Engines
Catherine is a coach who operates with Culdee on the Culdee Fell Railway. Over the years, she and Culdee have built up a strong working relationship, so he immediately knows if anything is wrong. She is very safety-conscious and was upset by Lord Harry's risk-taking when she worked with him. She is coupled in front, like other Culdee Fell Railway rolling stock, so she is responsible for warning Culdee about any dangers lying ahead of them.