Circle is the laidback hippy chick of the Underground. Friendly, relaxed and gentle, this helpful young lady is always willing to help Ernie and the other trains whenever she can and rarely, if ever, does she lose her cool.
Circle is painted light green with yellow stripes and doors. Her logo is painted on the sides of her carriage.
Series 1 - Pop Decoy, Sir Clunkalot, Mr Rails Never Fails, Brooklyn and Rocky Two-Shoes, Pulling Together, Caught Purple Handed, Ernie's Big Trip, Finders Keepers, The Magician's Assistant, Cover Story, Millie's Dream Day, Mr Movie Jones, Summer Breeze, Running Late, Light At The End Of The Tunnel, The Wreck Of Sea Shell Bay, Catnapped, Monster Mystery, Bon Appetit, A Change Is As Good As A Rest, Elementary, My Dear Bakerloo!, The Magic Lamp, How Great The Art, The Mayor's Visit, Techno Trouble, Snow Go