Series four was first released directly to video between 1994 and 1995 before its broadcast debut on ITV. The producers planned to introduce some new female characters, including motor car Caroline, Nancy, and The Refreshment Lady. Some commentators took this as a response to accusations of sexism levelled against the series two years earlier. In reality, these were not "new" characters, but creations of Awdry from the original "Railway Series" books. Series four was almost entirely based on "The Railway Series". The narrow gauge engines were introduced, and were the focus of a number of episodes. Only one original story ("Rusty to the Rescue", written by Allcroft and Mitton) was used, but this took certain elements of plot and dialogue from "Stepney the "Bluebell" Engine".