"Mavis belongs to the Ffarquhar Quarry Company. She was brought to switch the
sidings and was unreliable at first, but after she had helped to save Toby from
his tightrope, Sir Topham Hatt and the Quarry Manager decided to give her a chance
and allowed her to go down the tramway to Ffarquhar yard. Now she has become quite
useful, and she and Toby work the tramway very efficiently between them."
"Mavis is a feisty young diesel engine who has six small wheels hidden by
sideplates just like Toby's. She is high spirited and full of her own ideas,
often doing things without thinking about their consequences. Her lack of
experience often leads her into trouble, but she is smart and learns from her
mistakes."