A “beware book” kept by women working in Glasgow’s red-light district around the time of Emma Caldwell’s murder could be damning for police if its contents were uncovered, a retired detective has said. The book was used by women involved in prostitution to warn each other about potentially dangerous or suspicious clients, at a time when they felt they had to rely on “their wits and each other, not the authorities” to remain safe. Kept at the city’s Base 75 drop-in centre, the book contained information such as vehicle registrations, names, nicknames and descriptions of clients. One woman who wrote in the book claimed that the clients listed in it included “lawyers, police, all sorts”. The “beware book” was taken as evidence by police during the investigation into Caldwell’s murder in 2005. It has since “gone missing”. Stuart Hall, a retired detective, was tasked with seizing the book on his first day of the investigation. Stuart Hall worked on the investigation into Emma Caldwell’s murder “I never read its contents. But the book was seized, …