The man in Hertfordshire (not Dan Brown) to whom the letter was traced has this to say:
"Among my peers, there are people like me who believe that these issues deserve further attention ... There's a new generation coming through that strongly believes it's time to be a bit more open. I'm part of that generation." Besides, he says ominously, "Things are about to happen that will deserve attention."
Still no word on where the Holy Grail might be.