Smith is an outstanding book on many counts. Set in the author's favoured period, the mid-eighteenth century, the story owes its unerring sense of period partly to the characters. But though they are, you might say, period types … they transcend costumes, idiom, manners, because the author uses them to communicate more than just a sense of the past. This intricate mystery of ancient wrongs and present revenge has the kind of tempo and vitality we expect from Leon Garfield. Adventure is here, initiated when Smith … witnesses a murder seconds after he has snatched a document from the pocket of the victim. What the document holds, how Smith worries at its secret and what danger his curiosity brings—explanations follow logically on event in scenes in Newgate, in the streets of Holborn, on Highgate Heath—and for these scenes the author has first worked at background facts and then felt himself into the past. The prose in this book is noticeably less staccato than that of Devil-in-the-fog and there is more time allowed for reflection and for the proper emerging of character. For the reader is not told but shown how to understand that two paths converge—the path of the vagrant boy, independent, shunning affection, unwilling to trust or to like, and that of the magistrate who has to come to compassion a different way, by seeing the limitations of the legal form which has comforted his physical blindness. I doubt if anyone in 1967 will write a book so rich in the furnishings of historical fiction which offers also such a fascinating and such a valid study of human beings. (p. 935)

Leon Garfield's first book, Jack Holborn, marked him out at once as an historical novelist with an individual style. Mr. Garfield really knows the eighteenth-century scene and his background is impressively authentic. What gives this knowledge wings and makes him so readable is his command of a vivid, fast-moving prose. But there is something more than style and pace to [Black Jack]. The progress from Jack Holborn to Black Jack shows that as Mr. Garfield's appetite for his chosen century grows, especially for the macabre elements in it, so does his skill in telling his tale, while his interest has shifted beyond the picaresque rogues' gallery of his previous books. Now he gives us a compassionate treatment of the emotions of his chief characters that brings real depth to his new novel….

Mr. Garfield's prose style has always had distinction, but in this novel it is employed in service to a far better story than he has yet written. There is no disparagement intended in pointing out that it owes much of its vividness to a certain verbal device employed by Dickens, a constant cross-reference from material objects to human life….

[There] is a richness about this book, both in physical detail and in human feeling, that makes it a notable contribution to the genre of the historical novel. (p. 1369)

The Times Literary Supplement (© Times Newspapers Ltd. (London) 1968; reproduced from The Times Literary Supplement by permission), December 5, 1968.