According to the preface of this book, Charles Dickens' son remarked that these stories are real ones, told by real detectives. Supposedly Dickens, "consorting with the constabulary, was the obliging recipient of their confidences and reminiscences, and with his inimitable genius, he transformed them into fiction for our lasting enjoyment".
The book is noted as written "by Charles Dickens and other hands". These are stories that were in Dickens' Household Words magazine, so most are written by him, some by him with another, and the last 2 or so are just by others. All are enjoyable, tho, and the characters in them would fit well into any Dickens novel and leave you wanting more. Descriptions of the activities of gangs of thieves, or ways pickpockets worked, and ways the police used to catch them, etc. are most interesting, while often being almost chilling in their cleverness, especially knowing they were real events.