One of the films included in "The Fifty Worst Films of All Time (and how they got that way)" by Harry Medved and Randy Lowell.
The film invents a military order of "Castelaines" or "Castlers", of which Sir Giles (Robert Douglas) is the Master. In the source novel, these characters are Knights Templar, whom Sir Walter Scott invariably depicted as villains. It is unclear whether the change was made because of the Production Code (Templars were a monastic order, so hostile depictions might fall under the rules against negative depictions of clergy), or to avoid upsetting the Masonic Knights Templar, of which a number of distinguished Hollywood figures were members.