Do you think the Knights Templar possessed the Holy Grail or imbibed a secret version of Christianity banned by the Roman Catholic church? Have you heard that the Templars were set up by a secret society called the Priory of Sion? These and many more theories about the Templars drive mainstream historians mad. In this episode of Talking Templars, TV historian Tony McMahon flags up the conspiracy theories and Yale published academic Dr Steve Tibble shoots them down.