Sherlock Holmes: The Unauthorised Biography, by Nick Rennison

History and mystery engagingly combine to magnify Holmes's life

This new look at the mysterious sleuth is an entertaining mix of history, literary criticism and biography. It traces the story of Conan Doyle's famous creation through a careful reading of Dr Watson's accounts, combines this with research into the historical record and moves seamlessly between them. The reader becomes joyfully dizzy with confusion about what came from Conan Doyle's pen and what "really" happened in late-19th-century London.

The story of the great detective is a window on to the era at large. Nick Rennison explains that Holmes was "simultaneously a typical product of his age ... and a man at odds with the values and beliefs of the society in which he lived". The author uses this contradiction well, as a way of telling us about the period.

There are two kinds of history here. The first is an engaging and eclectic account of the Victorian era, and includes the Irish question, debates about Darwinism, the development of forensic science in criminal investigations and the popularity of opiates across the intellectual middle class. The second history describes the birth of Holmes as a national icon. Rennison details his appearance in public outside Watson's tales, beginning in adverts for Beecham's remedies, then on the professional stage, as a staple of amateur dramatic societies and, finally, on to the cinema screen.

People were convinced that he existed. So many letters were sent to 221B Baker Street that at one stage the Abbey National, whose address it was, employed a secretary to respond to the mountains of mail to the famous detective.

The author has created a narrator whose voice is that of the Victorian scholarly biographer, like those pilloried at the end of the era in Virginia Woolf's A Room of One's Own. This voice resembles the 19th-century gentlemen of letters. The brief interjection of a description of the A170, which runs through the village where Holmes was born, and the 1950s council estate at its edge, bluntly confronts us with the 20th century. Otherwise, the book could almost have been written during the era it describes. Beneath this serious voice is a humorous take on "Holmesian obsessives". Rennison has his fictional biographer push the reality of Holmes' existence beyond Watson's accounts. He distinguishes between "Holmes' real life" and his "parallel life in print". This is great fun, and the book is a welcome addition to the ongoing fascination with the stories.