This was the Holy Grail for a spy!
Grail of any pop music collection and prices will continue to rise sharply in the years to come.
With regard to the religious form of the story, recent research has again aided us - we know now that a legend similar in all respects to the Joseph of Arimathea Grail story was widely current at least a century before our earliest Grail texts.
It is thus demonstrable that the material for our Grail legend, in its present form, existed long anterior to any extant text, and there is no improbability in holding that a confused tradition of pagan mysteries which had assumed the form of a popular folk-tale, became finally Christianized by combination with an equally popular ecclesiastical legend, the point of contact being the vessel of the common ritual feast.
What this book was we do not know, but in face of the fact that certain special Fecamp relics, silver knives, appear in the Grail procession of the Parzival, it seems most probable that it was a Perceval-Grail story.