Isobella Gets Steamed is a cancelled episode of Jack and the Sodor Construction Company.
Isobella is jealous of the fun Jack and Alfie have when she is off-site. When it is time for the harvest festival, the vicar's tractor engine breaks down. Who can pull the float with the choir on it now? Isobella can, but she does not want to go off-site and miss out on all the fun.
But when she gets to the street and sees all of the people, she realises that she is having fun and that fun is what you make it.
Trevor was likely to have appeared.