Mavis first appeared in The Railway Series books by the Reverend W. Awdry before joining Thomas & Friends on television, where she works as the young diesel shunter at the Ffarquhar Quarry. Series 3, broadcast in 1991 and 1992, used the live-action model format that defined the early show. Her horn became part of her identity alongside the other engines' whistles and horns, helping young viewers tell characters apart by sound alone. Fans still isolate clips like this for edits, soundboards and nostalgia projects celebrating the classic era.