Lion (formely known by his number, 57) is an early steam locomotive, who had a top speed of 45 mph and could pull up to 200 tons. His brother was Tiger. Stephen said that Lion was confused with a diesel locomotive, as the both shared the same name.
Tiger (formely known by his number, 58) is the brother of Lion.
Planet is a locomotive that used to work on the Liverpool and Manchester Railway. Stephen commented that Planet loved to look at the stars every night.