There must be a different version of "The Holy Blood and the Holy Grail" that I haven't read, Brucie, if the scholarship in your book was beyond reproach--the book I read was full of "and if that happened, then this may have happened, and if this, why not something else..". The clincher of course was that in the introduction, the authors said that their book was based on a work of fiction which one of them had found on a rack at the airport.

There is a recent book about the Templars(at least it is more recent than HBHG), "Born in Blood", by John J. Robinson, that is based on history and fact, rather than speculation--even with that restriction, it is quite interesting--

As to the post above, if memory serves, the folks in Herefordshire have some empty caves that the Mercury has been trying to fill up with Could-this-have-been's--