The mystery starts with a document composed in 1971. It came from the Vatican, where the then-reigning pontiff, Pope Paul VI, issued an indult permitting what was known as the Tridentine Mass to continue to be said in England and Wales. What was striking about this document, which is generally only of interest solely to liturgists, was the fact that it came about as a result of a letter requesting the preservation of the traditional Mass signed by an eclectic list of notables, many of whom were not Catholic.