10/20 update: It appears Bushby has not published any new books in a few years.
The Bible Fraud by Tony Bushby has the inauthentic Pope Leo X quote on the cover. That turns out to be thematic.
Let's start with a summary of the plot:
Jesus married Mary Magdalene as well as two other women in his lifetime. Mary was a descendant of King Herod and Jesus was a descendant of a Celtic king named Lud. (I don't know how a Celtic managed to work his way to, and survive in, Jewish Palestine, where he'd stick out like the sorest thumb this side of Los Angeles.)
Jesus' line eventually fostered Constantine . However, Jesus and a twin brother named Judas Khrestus (?!) were "conceived by rape or adultery" between a member of Herod's family and the Emperor Tiberius.  Some stories in the Gospels, like the Temple cleansing, are actually about Khrestus  and this Khrestus escaped a sentence of crucifixion imposed by Caligula in 37 by appealing to an "age-old tradition" that allowed him to have someone sub in for him .
Judas later went to India to learn things . Jesus became a king of Britain named Cunobelinus  where he also joined a Druidic order  and acquired the name Bran the Blessed .
He was later captured by Rome in war  but escaped execution because of his connections with Roman aristocracy. He later went to Egypt to be initiated into mysteries  but sometime later was stoned to death .
Clues for this whole story can be found in all sorts of places ranging from conveniently inaccessible manuscripts to statues in France and even in the works of Shakespeare. Unfortunately, much of what would prove this has been burned by the church, and other things have been edited or interpolated to hide all this.
That's it. Now if you're still thinking this might have some credence, here's some particulars analyzed.
- Bushby thinks his book was predicted by Nostradamus .
- Many of his sources are -- conveniently -- "preserved in rare archival manuiscripts and difficult-to-find reference books." Among these sources are such items as the "Myvyean Manuscript"  in the British Museum. For some reason the only actual reference to this document anywhere online comes from references to Bushby.
And little wonder why. Tekton Research Assistant "Punkish" won the Gold Star of his life with this one -- he lives in the UK, and was able to contact the British Museum about this. His report:
I wrote to the British Library (who now house the manuscript collection that used to be kept at the British Museum) about this "Myvyean manuscript" and the official reply from Michael St.John-McAlister, the Curator of the Dept. of Manuscripts is this:
"I am afraid that I can find no reference to such a manuscript in our collections. We receive many similar enquiries relating to subject matter such as this and I have to say many of them are hoaxes or refer to non-existent manuscripts."
So much for Bushby as a credible source on alleged mystery documents.
- In addition, because many people will disagree with his book, Bushby will "not engage in written religious argument with readers" who disagree. 
The words "non sequitur" spring to mind.
- Sir Francis Bacon edited the KJV . Now this is an idea you do see offered up on some websites, but not one of them I have found to be of any academic bent. The source Bushby gives is by an author named Alfred Dodd who wrote some rather peculiar books like Shakespeare: Creator of Freemasonry. (He also appeals to "original documents" in the British museum that allegedly prove this, but are conveniently unquoted and unreferenced otherwise.)
The idea that Bacon had some part in the KJV is so outraegous that apparently not even the folks at Wikipedia are willing to let it stand.
Bacon is also said to have edited the plays of Shakespeare and added secret messages....on that one, I'll refer to a rather detailed discussion here by someone who passes the critical source test.
- Morton Smith is used as a source with his Secret Gospel of Mark and claim that a tombstone in Germany of a Roman soldier may have been that of Jesus' father .
- It's not quite The Da Vinci Code, but the Last Supper is used for an argument as it is claimed that one of the disicples (the fifth from the right of Jesus) looks like Jesus' twin, thus evidently showing Leonrado believed in Bushby's twin theory.
From what I see of that painting, that's as much imagination as Dan Brown offers to make John a woman; it is an idea also found on some conspiracy-theory sites, but the resemblance is highly superficial and the alleged "twin" has a chin that juts out rather more than Jesus'.
Michealangelo is also said to have endorsed this idea, as well as Raphael, but what Bushby takes for twin sons of Mary are always taken by credible art historians as the infants Jesus and John the Baptist. Bushby dismisses this by claiming that the boys are "identical" which is quite imaginative and clearly false.
The hairstyles and color are entirely different; the chins do not match, and little John already has on his prophetic garment, while Jesus is the only one with a halo.
- Also in common with Dan Brown, Bushby makes use of the legendary Abbe' Sauniere  who allegedly became rich thanks to some secret documents he found in a hollow pillar in his church in France. Olson and Miesel say it all in their comments in The Da Vinci Hoax:
[Suaniere] was in fact a simoniac priest whose wealth came from selling overbooked Masses until he was suspended by his bishop in 1911. The parchments were fake, the pillar was not hollow, and the tomb was not painted by Nicholas Poussin in his two works titled Et in Arcadia Ego. The so-called mystery was invented by a local restaurant owner in the 1950s to attract tourists." 
- "Old records" of unspecificed origin and nature tell us that the Pharisees were founded by a "Pharez" who "developed a school of Predestination" and the Sadducees by one "Sadoc" who was "a disciple of Antigonus Scohaeus" who had allegedly founded a "School of Infidels". 
Needless to say this is a mix of fact and fiction. The name of the Pharisees comes from the word perushim, which means separatists. "Sadducees" is perhaps properly taken from a "Sadoc" -- one of Solomon's priests in the OT, whom they regarded as their ideological ancestor, if the derivation is correct -- others argue that it comes from a Greek word for "fiscal officials" but a connection to this alleged Antigonus is not one of the options scholars use.
Of course there are no other references to this "School of Infidels" or this Antigonus online, expect from those copying Bushby.
- The Essenes are connected with the Druids of Gaul .
- Even if the quote from Julian is correct  it has the facts mangled; Paul, Matthew and Mark all equate Jesus with divine Wisdom.
- Bushby repeats Harpur's argument about KRST .
- Bushby claims he made clergy "squirm" by asking about where Jesus was called a glutton and a drunkard. Such names were simply stock rhetoric of the time; just as the the Pharisees were not actually vipers and hypocrites, and also whitewashed walls .
- The Gauls are the same people as those who lived in Galilee .
- A microcosm is offered of Remsberg's list .
- Bushby repeats an Anglo-Israelist argument I last saw used by Herbert Armstrong  that "British" combines the two Hebrew words for covenant (berit) and man (ish). More serious sources connect the name to that of a tribe of Picts, the Pritani. Also the home of Mary Magdalene, Dalmanutha , is in South Wales.
- Paul  at one point had to flee to Wales and there was protected. One source for this information is "an ancient manuscript in Merton College".
- Bushby uses the "Bacchus on the cross" gem of Freke and Gandy  -- yes, the one that's a forgery -- as well as offering all the usual copycat candidates (Mithra, Attis, etc.)
I really see no need to say more. The ideas Bushby propounds lend little credence to the rest of what he writes, though of course anyone who wishes to have me look into specific claims made by Bushby is welcome to request that I do so.