In the novel Hickory Dickory Dock, Jean Tomlinson is a resident of the hostel on Hickory Road owned by Christina Nicoletis. Unlike many of the other residents, Jean is not a student but works full-time as a physiotherapist at St Catherine's Hospital. Jean has a reputation for being upright and straight-laced. Some of the other residents call her “pious Jean” and rather disliked her.
Jean is a friend of Mildred Carey, a senior dispenser at the pharmacy in the hospital and as such, visited the pharmacy occasionally. This initially made her a suspect in the theft of a bottle of morphine which had been used to poison Celia Austin. Jean told the police about the bet which Nigel Chapman had made concerning how he could easily get hold of three types of deadly poison.
Towards the end of the novel, Jean also told Valerie Hobhouse that she had discovered that Nigel Chapman has two passports. Jean insisted she came to know this because she opened the wrong attache case (Chapman's) by mistake but Valerie doubted this since her case and that of Nigel look very different. Nonetheless Valerie was able to give Jean a plausible explanation for the two passports. Patricia Lane's life was endangered for knowing just such a fact. Nonetheless, nothing happened to Jean at the end of the story.