Stephen is one of the earliest engines ever built. Newer engines may be faster and stronger than Stephen, but what he lacks in terms of strength or speed, he makes up for with his positive spirit, sense of humour, and knowledge. He used to work at docks and in mines, but now works as a tour-guide at Ulfstead Castle. He can often be seen pulling an open-topped carriage and was trapped in the Ulfstead Mine where he discovered King Godred's long lost crown in time for the opening of the castle. In the seventeenth season, he gave Percy a lucky horseshoe when he was having bad luck, helped him trick James and took the Afternoon Tea Express.
Stephen is a jolly old engine with a positive attitude and a good sense of humour. He is a good-hearted and quick-witted engine, and will not take any nonsense from engines like Spencer or Diesel. Some of the smaller engines look up to him for advice, and he is always willing to get the job done.