Toby is the oldest and wisest of the principal characters.  Toby is a branch line steam tram, whose over-riding feature is square-ness. Both his face and body are square, and his body is wood, not metal and he can travel forwards and backwards, so doesn’t need a turntable. He's very proud of his cowcatchers. 

He was rescued from the scrap heap by Sir Topham Hatt.  He’s even more vulnerable than sickly Henry, because as a tram, he isn't as fast or strong as even the smaller engines. 