The Book of Magic or the book of Robert Findhelm refers to a book written by John Uskglass, the Raven King, in his own invented script known as the King's Letters. The contents of the book were the prophecy of John Uskglass. It is not to be confused with a book of magic.

The origins of the book are shrouded in mystery. According to Gilbert Norrell, even its existence was a controversial topic in magical literature. For an unknown period of time up until 1754 the book was in the possession of one Robert Findhelm, a substantial farmer, into whose family it had passed after the suppression of the abbey of Easby. Findhelm apparently knew about its peculiar nature and considered himself as foremost the Guardian of the Book, although personally unable to read it. In 1754 Findhelm instructed his servant Clegg to take the book to a man in Derbyshire. During his journey however Clegg became involved in a drinking contest, where he ate the book as a challenge. Four years later, while on the run, he had a child with a servant-girl [30]. The child, Vinculus, was born with the King's letters imprinted on his body [67].

When Vinculus was seventeen he sought out the man in Derbyshire, who was in fact the very last Reader of the King's Letters. The man translated the writing---a prophecy---for Vinculus and died shortly afterwards [67]. Vinculus then became a street magician, and during the years of the Revival of English Magic he dictated the prophecy to its apparent subjects. (See: Prophecy of John Uskglass.) In February 1817, when the prophecy had seemingly been fulfilled, the writing on Vinculus' body changed into a new work. That spring Childermass brought Vinculus in front of an assembly of magicians in York, where presumably they collectively studied the new book [69].