Elsie was created by the Reverend W. Awdry, but was not featured in any Railway Series stories. A model of her, however, was seen in Awdry's model set of Thomas' Branch Line. She was mentioned in The Island of Sodor: Its People, History and Railways, and also appeared in The Railway Series: Surprise Packet, in which a stationmaster asked Toby to move two trucks to two different depots before he could couple up to his coaches.
Elsie is based on the GER Wisbech and Upwell Tramway luggage van No. 9.
Elsie is painted brown with the letters 'NW' painted on her sides in yellow.